I have played NWN2, Baldurs Gate 1+2, Planescape Tornment and lots of other RPGs (and other genres).
NWN has the most complex character creation I have ever seen and even I was very confused when I played it the first time. And when I read the forum here on gog, it looks like many other people have questions too. I try to answer some of them.

Some statements first:
-I am talking about NWN2 as you get it on gog, no mods or other things
I am NOT talking about pvp and I assume that you are in a group together with other npc.
-This is from a beginner for beginners. If you know what you are doing, you can completely ignore this.
-I am the straight forward type. This means, my characters are focused on doing one thing very good. If you want a char that is good in several different things, ask somebody else.
-Please make comments for what of these things are different in NWN1.

Character design
When you cannot go on in this game, it is most likely because you cannot win a fight. A dumb char with no dialogue skills might not always get what he wants, but he will be able to finish the game.
When talking about good chars, I mean chars that are good in fighting

The first question you should ask yourself is: how is the char supposed to fight?
This leads to: do you want to use weapons or magic?
For beginners, fighting with weapons is easier because if you use magic you need to know what spells you need in which situation. There are hundreds of spells and even I have problems to tell which one is most useful now.
Whatever you do, focus on one fighting style and try to be perfect in this one.

You have the choice between the following combat styles:

-fight with a two handed weapon:
This is the easiest way. Take the biggest weapon you find and start killing. Those chars need tons of strength, because the (strength modifier * 1.5) is added to your damage when using a 2-handed-weapon or holding 1-handed-weapon in both hands. High strength means also a high chance to hit.

-fight with a weapon in each hand (dual wielding)
These chars need lots of dexterity and the feat weapon finesse. Use only small or tiny weapons and take all 2-weapon-fighting feats. Else you will never hit anything. Strength is not so important, because damage bonus is halved for off-hand-weapons.
In order to do lots of damage you need:
-highly enchanted weapons
-additional elemental damage
-class abilities that cause damage independent of weapon damage (such as sneak attack)

-fighting with weapon and shield
You lose damage and increase your chance of not getting hit. I think this is only good for divine casters.

-When you want to fight with magic, you have the choice between arcane and divine magic.
Divine magic can heal, protect, hinder enemies and cause damage and it can be cast while wearing armor. Arcane magic does often more damage and there are also lots of spells that protect you and weaken the enemy, but wearing armor causes a chance of spell failure. Arcane casters also have the lowest hit points of all classes. If you are a beginner and you want to use magic, divine magic is usually the easier choice.

Magic users can also be divided in two other groups. Those who can learn every spell but they need to memorize each spell when resting and those who select spells to be learned only at level up, but they can use any spell they want until their uses per day are used.
Learn all spells learn spells only at lv up kind of magic used
Cleric, Paladin Favored Soul divine holy
Druid, Ranger Spirit Shaman divine nature
Wizards Sorcerers, Bards arcane

A beginner should choose a class that can learn all spells, because it is often hard to tell which spells will be most useful in the future.
Paladins and Rangers are more fighters than casters. There are also warlocks, who learn few unique spells, but they can cast it infinite times.

When talking about combat efficiency you should consider 3 things:
-The ability to cause damage. A good offense is the best defense. If you kill enemies fast, they have little time to harm you.
- The ability to avoid being hit. With high armor class and high saving throws, you don´t need to care what the enemy does.
-The ability to take hits. Lots of hit points and damage absorption are always good in case the first two things do not work.
Example: Imagine you fight a mage who casts only fireballs. You can:
- Kill him with a sneak attack or a death spell before he can do anything.
- Have high reflex saves and evasion feat. He will never hit you.
- Cast immunity from fire on yourself and do whatever you want to kill him.

-Classes and multi classing
When you know what kind of char you want to have, you have to choose what classes you take in order to reach your goal. There are 2 kinds of classes. Normal classes can be chosen at the beginning of the game and any time later. Prestige classes require some skills and feats from normal classes to be taken. Plan your character carefully from starting level to final level before starting the game. Think about following questions:
-What is the maximum level I can have? (It is bad when you take a class because it learns a great skill at level 20 and suddenly you find out, the max level in your campaign is 15)
-What are the requirements for each class? (A Paladin must be good and a warlock must be evil. It will be hard to multi class them)
-You can have only up to 4 different classes. (up to 3 classes in NWN1)
-How do the abilities of the classes work together? (Good example: as fighter you learn cleave to hit more than one enemy and as frenzy berserker you learn to hit enemies twice when you cleave. Bad example: With your first class you learn power attack (can only be done with big weapons) and then you become a ranger to learn 2-weapon-fighting (should be done with small weapons)). Remember, that some good abilities can only be done with a special kind of weapons or while wearing no armor.
-If you take more than one normal class, be careful not to get exp penalties. This happens, when you have at least 2 normal classes that are not your favored class and they are more than one level apart.
-Think about the race you choose. Some races have higher ability scores (dex, int, … ) or other nice things (spell resistance) but they level up slower. This is not a good choice for beginners. Halflings and gnomes are small so they cannot use large weapons and they
use medium weapons with 2 hands. If you are unsure what to take, use a human.
One final thought about multi classing:
Classes that fight with weapons are often good for multi classing. Magic user should use only prestige classes where they continue to learn spells in their normal class or not multi class at all.


Some suggestions for straight forward classes from level 1 – 20
Note: these are just suggestions. You can do whatever you want.
Look in game what skills and feats you need for the prestige classes.
When I take non human races you can always use humans if you want. I try to take the race with the best ability scores.
The warrior:
Requirements: non lawful alignment,
Stats: (shield dwarf) str 18, dex 14, con 14, int 14, wis 8, cha 6, increase str at level up
Classes:
6 levels of fighter
5 levels of frenzy berserker (for improved power attack)
1 more level fighter (you don´t have enough feats for weapon master now)
7 levels of weapon master (choose a 2 handed weapon as weapon of choice)
1 more level of fighter
Feats: first you take the feats required for the frenzy berserker, than those for weapon master.
Take nothing except the required feats or else you will not get the best things from both classes until lv 20. Once you are weapon master, take blind fight.
Pros: very good melee damage, very easy to play (just click on the enemy and it will die)
Cons: cannot do anything except melee damage
Note: This was the char of my first play through in nwn2. He made more damage than all npc friends except some high level spells. But he never run out of “spells” because his magic wand was a great sword. In MotB I took 10 levels of dwarven defender because I got lawful good at the end of the OC.


The Thief:
Stats (tiefling): str 12, dex 18, con 14, int 18, wis 8, cha 8, increase dex at level up
Classes:
1 level rogue
3 levels swashbuckler (add int bonus to damage)
10 more levels of rogue (11 total)
6 levels of duelist (int bonus added to armor class while not wearing armor)
If you want to go up to level 30, take 10 levels rouge, 14 levels swashbuckler and 6 levels duelist.
Feats: all two weapon fighting, able learner (you have tons of skill points and you want to increase your rouge skills when you take levels as something else), blind fight
If you go beyond level 20, take crippling strike at rouge level 10 and epic precission at level 21. This way you can sneak attack all enemies.
Pros: high melee damage with lots of attacks, sneak attack and precise strike, lots of skill points,
With high dex, high int and a mage or monk robe (via use magic device) he has a higher armor class than the warrior in his full plate
Cons: needs sneak attacks for good damage
Note: dual wield small piercing weapons (short sword, dagger) with high enchantment bonus and additional elemental damage


Edit: I wanted to add some more, but it does not want to post what I copy from the text on my computer.

The Priest:
Requirements: lawful good alignment, deity kelemvor
Stats: (aasimar) str 14, dex 10, con 14, int 12, wis 17, cha 16 increase wis to 20, then increase cha
Classes:
1 level cleric, select the two following domains: earth (more hit points and stone skin spells), air (more damage spells)
3 levels of paladin (higher saving throws, immunity to fear and disease)
Continue as cleric until you can become a doomguide
10 levels of doomguide (immunity to death spells, many divine feats)
All remaining levels as cleric
Feats: spell caster prodigy at level 1, practiced spell caster (cleric) as soon as you have all feats required for doomguide, extended, persistent and empower spell if you like casting or power attack and more divine feats if you like fighting.
Pros: very good in casting and turning of undead, even useful in melee combat, more hit points than most casters, casting in full plate and shield, immunity to several dangerous effects
Cons: less melee damage than warrior or thief and less magic damage than the mage (except when fighting undead), little skill points and you have to spend them on concentrate, spell power and diplomacy
Note: for role playing reasons, let him fight with the holy avenger and if you go for epic levels, teach him the epic spells vampiric feast and summon balor (you have observed your enemies carefully and learned to use their best tricks against them)

The mage:
Requirements: human, evil alignment
Stats: str 8, dex 16, con 14, int 18, wis 8, cha 8, increase int at level up
Classes:
6 levels of wizard (necromancy school)
7 levels of arcane scolar (lots of meta magic feats)
1 level of pale master (plus 2 armor class and plus 2 hit points)
All remaining levels as red wizard (Learn all illusion spells before becoming a red wizard. If you go for epic levels, take one more level of arcane scolar and more wizard levels until you can cast level 9 spells. Continue as wizard after having all levels of red wizard.)
Feats: spell caster prodigy and able learner at level 1 since you will get more skill points than class skills, extended and persistent spell, this char is good for item creation
Pros: At high levels, no one can make more damage than you and you can protect yourself from almost everything, many skill points
Cons: useless in fighting with weapons, very little hit points, it is hard to survive at low levels
Note: This one is not a good choice for beginners. Until you learn some powerful spells every enemy can kill you with a single hit. For role playing reasons, make him lawful evil, specialize in conjuration and call him Edwin. If you played his personal quest in Baldurs Gate 2 you can make a female mage and call her Edwin still.

General game play tips:
-Save often and in different slots (this is true for almost every game)
-When a fight is extremely hard, look what your friends are doing. Sometimes your group members will do nothing at all and say something like “What should I attack?”. Solution: Whenever you change party members, hold down right mouse button and issue command “attack nearest enemy”. Then select another char and do the same thing again so the char you controlled before will attack too.
-Sometimes your group will run after enemies when you don´t want to fight them where they are. This will result in your party being scattered widely and fighting tons of enemies at once. When you tell them to go somewhere they will go some steps and return to the enemy they fought before. Solution: Take your group to the place where YOU want to fight. Tell them to wait there. Take a tank char and go on until an enemy spots you. Run back to your group and wait until the enemy arrives.

Good work on this; I'd agree that NWN character creation is a daunting process. I might add a few build examples of my own, as well as a complete Sorcerer spell list for those who want to play one.

Some general feedback: I would add that such characters should pick a weapon that has a high chance of critical hit or deals extra damage on a critical hit. For Neverwinter Nights 2 the "Falchion" and "Scythe" are great two-handed weapon choices in this respect. In NWN1 there is no Falchion, so the next best thing is the Greatsword. There are a couple cases it can be useful. Low-level characters tend to do well with this. The other case is Paladins who rely heavily on the Divine Might feat, since the bonus damage it adds is the same for both 1-handed and 2-handed weapons.

I greatly enjoyed my MotB playthrough as a solo Paladin/Blackguard; obscenely high AC and saving throws, and use Divine Might (and later epic divine might) for my damage output. As an additional point, arcane casters also have the lowest chance to hit in combat of all classes.

Bards and Warlocks can cast in light armor (and with medium armor with a special feat), and their spells have their own unique flavor. They are generally referred to as the "prepared" spellcasters and the "spontaneous" spellcasters respectively.

I'm always torn as to which kind to recommend to beginners. On the one hand it's easier to try out new spells with a prepared spellcaster, but on the other hand it's much more straightforward to play a spontaneous one if you do get your spell selection right. To be more precise, a Paladin must be lawful and good, while a Warlock must be chaotic or evil. It should be noted that the Paladin's "Divine Might" feat requires power attack as a prerequisite. Although I've never built a two-weapon Paladin, using Divine Might would be absolutely a top priority. There's a hidden gem in the Sun Elf. Normally you need to take a level-up penalty to get access to an intelligence, wisdom, or charisma bonus. The Sun Elf is the one and only exception to that rule, granting +2 intelligence with no level-up penalty. For wizards, that's awesome.


Here are a couple additional pieces of advice:

Spellcasters
Every spellcaster has a primary spellcasting stat (except the Favored Soul and Spirit Shaman, which have it split into two attributes - ugh). Pushing this stat higher increases the maximum spell level you can cast, so bards will want 16 charisma and wizards will want 19 intelligence before the end of the game to get access to all their spells. It also increases the number of spells you can cast, but not by a very large amount. For people who cast spells mostly for defensive or buffing purposes, this means having the bare minimum stat necessary to access all your spells is a good idea.

However, for those who want to use their spells offensively another issue rears its head: difficulty class, or "DC". A spell's DC is basically equivalent to a warrior's attack power, making the spell harder to dodge or resist. More powerful spells have a naturally higher DC, but it can also be improved by raising your casting stat. A high DC is very important for spellcasters who want to use their magic offensively, and they should seek to maximize their casting stat if at all possible.

The "spell focus" feats can also be used to increase the DC of your spells, but they only apply to a few groups of spells. Generally the conjuration spell school is the best for low-level characters (though not so much for high-level ones), while necromancy has a lot of great instant-death spells that really benefit from high DC's at higher levels. Transmutation, Enchantment, and Evocation are also decent choices for spell focus.


Wizard
One option you will have when becoming a wizard is picking your specialty school. This is a misdirection, what you're really picking is your opposition school (spells that will be barred to you). It's always a good idea to specialize, but some of the choices are really bad.

Conjuration - lose transmutation
NEVER ever do this. There are a million and one reasons, but the biggest one is that you lose out on the haste spell. That alone is reason enough to look elsewhere.

Abjuration/Evocation/Transmutation - lose conjuration
Only do this for epic-level characters. Pretty much all of the best low-level spells are conjuration, so you will suffer immensely from level 1-10 if you choose any of these options. It's doable for epic though, since there aren't many great high-level conjuration spells.

Divination/Enchantment - lose illusion
A lot of your best defensive magic is from the illusion school, so you'll be very vulnerable if you choose these options. Still not the end of the world.

Illusion - lose enchantment
Not a bad choice. You lose out on some nice buffs and debuffs, but the wizard is literally oozing with buffs and debuffs so you should be able to find replacements. It should be noted that if you're aiming for the "Red Wizard" prestige class, the illusion specialization is the only option if you want to retain full access to illusion spells. Every other option will bar illusion (either originally, or after joining the prestige class).

Necromancy - lose divination
Far and away the best choice; there is only one really good divination spell in the entire game: "premonition". Of course, that just so happens to be your best high-level defensive spell, so this is a fairly heavy trade-off for epic level characters. Low-level characters won't even feel this.


Sorcerer
Some must-have spells:
1 - Grease, Magic Missile, Summon Monster I (aka the "impromptu minesweeper")
2 - Cloud of Bewilderment, Invisibility, Mirror Image
3 - Haste, Dispel Magic, Stinking Cloud
4 - Evard's Black Tentacles, Stoneskin, Improved Invisibility
5 - lesser mind blank
6 - Isaac's Greater Missile Swarm (IGMS)
7 - Energy Immunity
8 - Premonation

It's generally a good idea to have at least one version of the "spell mantle" and "spell breach", though which level you get it at is up to you. Damage spells are, with few exceptions, quite overrated. They're important in Neverwinter Nights 1 where you will be spending a lot of time solo or with only a single henchman, so being able to deal damage yourself is important. In NWN2 you'll be spending most of your time a larger party so it's more helpful to incapacitate enemies than to damage them. I'm not saying to ignore them entirely, just saying they're not high priority.

Thanks Darvin
About your:

"I greatly enjoyed my MotB playthrough as a solo Paladin/Blackguard; obscenely high AC and saving throws, and use Divine Might (and later epic divine might) for my damage output. "

How did you do the alignment change to be a paladin AND an anti paladin? Does the saving throw bonus from both stack?

I´d like to be an evil char (something like fighter/blackguard/assasin) but in any game with alignment changes I end up being lawful good (or something similar if it is not DnD). In bg1+2 I played through with an evil thief, but I played good and choose this alignment only to use some typical thief items (some items can only be used by evil chars). Your job is to save the world after all. The only RPG I know that has an evil option for the main plot is arcanum.

I just realized my "table" about what classes use what kind of magic looks terrible.
I wrote this text in MSword and copied it here. Looks like some uses of the space button have been lost while copying.

I used a terminal command to switch his alignment halfway through character creation. Theoretically there are sufficient evil alignment shifts in the original campaign that I could have done this legitimately. However, this character was built specifically for MotB only so I just hand-waved over it.

Yes, the saving throw bonus stacks. You can also add the Warlock's "dark one's luck" invocation to stack the bonus three times, if you're so inclined. However, more important is getting one level of cleric with water domain; this gives you evasion and allows you to change your deity (which, having started your career as a Paladin, is probably something no longer appropriate). Also make sure to qualify for Epic Resilience, since your saves will typically be so high that the "fail on natural 1" becomes problematic. Once the build is complete, you won't need immunity items because you will actually be effectively immune to everything that allows a save. The OC doesn't really support much more than petty villainy, I'll agree. That said, MotB has some pretty evil choices available in it, particularly if you intend to create the amulet of betrayal incarnate (which, due to its penalties, is basically only useful for a Paladin/Blackguard)

There's a very nice web based character builder at nwn2db(google it). Also has sharing, comments, forums etc. Requires a free account to save but not to use.

It is true that there are tons of builds on nwn2db.com.
Sometimes I look there to see what ideas other people have.

But:
-there are builds for different purposes.
Some are for the OC or similar campaigns, some are for persistend worlds, some are for PvP, sometimes someone wants to show what crazy things he can invent, some are for role playing and others are just junk.

You need to know the basics to understand what is what and why did they do it this way.
Some of this is explained here.

-The forums and comments are full of bizarre abriviations.
If you get this game and you want to play the OC for the first time, these builds and forums will be as hard to understand as a book about quantum physics. (I know what I am talking about because I work in a physics institute. unfortuanatly the name "Madscientist" was already used.)

I think, what I have written is relatively easy to understand.
This is to avoid something like this: In one forum someone asked:" why do I never hit anything?". I turned out that he was dual wielding katanas without having the exotic weapon feat or any dual wielding feat. This is something you cannot know when you play it the first time. you just think: "Ok, the katana is the one handed weapon with the biggest base damage. And when I take one of them in each hand I will do twice as much damage."

There is also a guide for character creation on gamefaqs.com. But it is relatively complicated and he gives many different rules for creating the perfect char. I had to read this several times to understand the what he is talking about. and I ignored most of these rules in the suggested builds above. This game is not so difficult that you need a perfectly optimized char to finish it. It is enough when you understand some basic rules and you know what you are doing.

note about the thief: In some guides is written, that the precise strike of the duellist does not work when dual wielding. So duellist will give you only ac bonus and a haste spell. So you can use any small weapons that works with weapon finesse. You don´t need a piercing weapon.

Well, here's a character build I've been having fun with lately. Technically I'm playing him with NWN1, but it was pretty easy for me to adapt him over to NWN2.

Human Fighter / Rogue / Weapon Master
STR - 16
DEX - 14
CON - 14
INT - 14
WIS - 10
CHA - 10

This dilettante provides a very balanced character, with many skill points and superb melee combat potential. By mixing in one level of rogue every three levels, he can master several skills and has an incredible selection of class skills at his disposal (hint: save as many skill points as possible before taking a level of rogue in order to take advantage of his selection of class skills). His skill as a weapon master makes him a true force of nature in melee combat. Every time you get a stat increase, put it into strength.

Notes:
* If playing in Neverwinter Nights 1, there isn't as much impetus to focus on fighter. This is because there are no "greater weapon focus" or "greater weapon specialization" feats in NWN1. As a result, once you've finished with weapon master a 50/50 split with the rogue makes a lot more sense.
* This build will work for any race which has an appropriate favored class (fighter/rogue/any) and doesn't have a penalty to STR, DEX or INT. You will lose Luck of Heroes if you do this (which is your human bonus feat; this build has low will saves).
* If you wish to create a scythe weapon master, you can easily trade Luck of Heroes for exotic weapon proficiency. While I recommend the greatsword (since there are some nice greatswords) other weapons also work well, such as the falchion.

1 - Rogue - Luck of Heroes, Dodge
2 - Fighter - Weapon Focus (greatsword)
3 - Fighter - Mobility, Combat Expertise
4 - Fighter
5 - Rogue
6 - Fighter - Spring Attack, Whirlwind Attack
7 - Weapon Master
8 - Weapon Master
9 - Rogue - weapon specialization (greatsword)
10 - Weapon Master
11 - Weapon Master
12 - Weapon Master - improved critical (greatsword)
13 - Rogue
14 - Weapon Master
15 - Weapon Master - power attack
16 - Fighter
17 - Rogue
18 - Fighter - cleave, great cleave
19 - Fighter
20 - Rogue
21 - Fighter - greater weapon focus, great strength
22 - Fighter
23 - Fighter - epic weapon focus
24 - Rogue - overwhelming critical
25 - Fighter
26 - Fighter - greater weapon specialization
27 - Rogue - epic weapon specialization
28 - Rogue
29 - Rogue - crippling strike
30 - Rogue - epic precision

Wow, I used almost same for the OC of NWN1.

He had a wis of 8 (you have 30points in NWN1 and 32 in NWN2), took blackguard instead of weapon master and used a scythe. Lots of damage, good in staying alive, many useful skills. With "use magic divice" he can even cast spells.

I took two points out of constitution to create a bit of a glass cannon. He still has sufficient hit points for most purposes, though.

Right now I'm about level 26 with this guy in HotU (fighter 10 / rogue 9 / WM 7), and he's a bit of a terror in melee combat, typically getting 1-2 crits per round and hitting for over 100 damage on a crit. My weapon is a +6 keen acidic greatsword. I've got an entire page of my inventory filled with scrolls for UMD purposes. Spell Breach is a particularly nice one; saves me having to hack through magical defenses.

Thing about Blackguard is that he needs charisma to get the most out of some of his skills. I'd probably go with an array like this for that prestige class:
STR - 16
DEX - 12
CON - 14
INT - 12
WIS - 8
CHA - 14

Scythe only requires martial weapon proficiency, not exotic, so no additional feats are required (it was an exotic weapon in NWN, but this was changed in NWN2). Scythe is also one of the best choices for a weapon master because of the massive critical multiplier (x4). The critical threat range may seem unimpressive at first, but once you factor in Improved Critical and Ki Critical the range becomes 17-20, which will have you dealing plenty of criticals, and with absolutely massive damage.

Gah, I always get stuff like that mixed up between the two games.

That and I occasionally play Pathfinder so I have three versions of the rules to confuse myself with <_<