Apologies for yet another topic on the issue.
I need some help with Mage builds. I started one last night but don't mind starting over because I'm not far in.
I went for male elf, Only Child (or whichever one it is that gives you +6 WP) and out of the starting five, pumped 4 pts into Charisma, one into Harm. I have since put 1 more into CHR to raise it to 9, 2 points into Persuasion and took Agility of Fire.
I think I'm level 5. Immediately got Sogg and Virgil. I aim to play with a lot of NPCs.

I think I'm pretty much on the right track here (aim is to powergame). My goal is diplomacy and maximising experience through Harm spam. I want to go 100 magical aptitude.

Where to go from here though?
Was 15 CON the goal (together with the Elven amulet for +4)?
Dex 20 eventually, right? With AoF.
Are there any real benefits in investing into Beauty towards the late-mid game once points don't really matter so much?
Am I forgetting anything?

That basically sounds like you have a good setup/idea of where you want to go. The Only Child background is going to give you a huge, early game advantage in terms of how many spells you can invest points in without having to spend points in Willpower. But if you are mainly going to focus on harm (as a way to level quickly) then that isn't as important.

Since you are going to have a lot of followers you, I feel, either don't need to worry too much about Dexterity (because even though yes, having a high dexterity is good in terms of allowing you to cast more spells per turn, you don't actually need that protective barrier of spells because you will have so many followers). But that is my opinion, and you are definitely able to have that many followers and still be doing all/almost all of the fighting yourself (because with 20 Dex and Harm you are going to be killing most things in your first turn of combat).

I never felt it really necessary to have such a high Constitution, especially, again, with so many followers (since if you need to drink a fatigue potion you have followers who will take up your slack in terms of damage dealing in fights). But again, that will mean you'll be able to just keep casting spells without fear of fainting.

Beauty, never matters unless you are specifically playing a character with either really high or really low beauty. Low is bad - everyone hates you. High is really good because everyone loves you. But it certainly doesn't matter if you have average beauty the entire game.

If you are trying to get to 100 Magical Aptitude quickly you want to spend the next few levels investing points in spells, until you have 100 aptitude basically. If you're only level 5 you'd definitely fine just sort of throwing points around into spell colleges (I'd go for White Necromatic for healing, Conveyance for teleport, and then Temporal if you want to have even more action points per turn (Haste/Tempus Fugit) or you want to not spend as many points in Dexterity and instead put points there, and then if you want to continue the Fire or Black Necromatic colleges you can since you have a point in each already).

Hope that is helpful.

Thank you, kind sir!
I pretty much needed a confirmation that I was on the right path.
Isn't it strange how Arcanum has such an incredibly complex and in-depth character development system, yet there are virtually no guides on how to build anyone specific? I guess it might also be up to the fact that it's so flexible that unless you cock it up big time, you will be able to remedy mistakes within a few level-ups.

Also, someone mentioned in another thread, I think in GD, that they are 7 by the time they reach Shrouded Hills? How do you do that? I typically clean out the area, loot everything, get the quest from Brago, kill Fahrkus, empty out the wolf passage et voila I'm 5.
Or did they simply get lucky (or unlucky) with ~3xBrown Bear random encounters?

And just to reaffirm, there isn't a way out completing Jongle's steam engine quest without killing Hervor, is it? (Obviously other than snitching on the poor mage)

No problem!
I feel like I remember there always being a decent amount of discussion about how to build characters and what worked well with each other and such when the game first came out/in the following years (when the forums were quite active). But I think a lot of that meant that no real, written guides were compiled, instead it was stuff asked in threads, people pointing new people to older threads, and so on. And eventually everyone either had played enough to know what they were doing, or could figure it out, or there weren't new people coming to the game.
And so with the sort of reemergence of Arcanum through GOG (which is great!) it has meant that the demand for things like guides or walkthroughs, which has not been important before, has increased, and so we notice things like a lack of guides (especially since the old forums are gone). I don't remember if I've ever gotten to level 7, that does seem quite high. I'm pretty sure I always get to level 5 though before Shrouded Hills. Yeah unless you somehow get some random encounters on the way to Shrouded Hills I don't know where you can get more experience than what you suggested (make sure to get all of the wolves in the mountain pass: I think there are four or five after the Wolf and Ailing Wolves right at the beginning of the pass). Nope, there isn't if you want to do the quest for Jongle. Hervor has to die somehow basically, because he won't let you touch his steam engine.

I actually just wrote a guide over at GameFAQs because there was no quality character creation/development information 10 years after this game was released. It's the one listed as just 'FAQ' by Leonidusx. In particular there is a section which gives easily found good items early on in the game. For example, you can steal some awesome magic robes from the magic item shop dealer in Blackroot (use a fate point if you don't want to kill her). One of the best magic helmets in the game is in the ancient maze near Durnholm.

Constitution is a completely garbage stat, as you get hp and fatigue from levels without spending character points. The other minor benefits from it (and even poison immunity when it's 20) are also entirely worthless compared to any real CP investment alternatives.

Same thing with beauty. Almost entirely worthless. If you're even that concerned with beauty, there's many things which give free boosts to it (beauty amulets, blessings, etc.) without spending points.

I would say you should get your dex to 20 without the use of agility of fire, especially if you use followers because then you can spend your maintained spells on them. If that doesn't interest you, then spending 4 points in INT to get 1 more maintain to use agility of fire on yourself to get 4 points of DEX after spending time in battle to do it is also a little self defeating. I should note you can get the magical gloves of dex from the elven trader in Ashbury, and the enchanted warboots which give +5 speed are sold commonly at stores. The bonus speed at 20 DEX really is nice man, but only if you are using turn based combat.

You probably already know this, but INT is really only as necessary as you want it to be on a mage. If you plan on using a lot of sustained spells, then you need int. Otherwise, you can leave it at 8 as long as you want (which is enough for tempus fugit and then hasten, I might add). A lot of people I think really overestimate the importance of INT on a mage.

Since you want to get your MA to 100, I'll list what spells I recommend:

Harm
Minor Healing
Strength of Earth
Agility of Fire
Firewall -> Fireflash
All 5 time spells
All 5 Conveyance spells (teleport wooooo)
Shield of Force
Charm -> Stun

If you need more MA, you can continue past shield of force to get disintegrate, though usually disintegrate's drawbacks make it not worth using (50FT cost, destroys the corpse and thus items on the corpse).

If you don't like to quickload, you can always finish white necromantic for ressurect.

Lesser choices for raising MA (these spells are not highly recommended but are ok):

Charm Beast -> Entangle
Finish Phantasm to get Invis
Finish Mental to get Dominate Will

EDIT: As far as level 7 before shrouded hills goes, there is a way to complete the arbalah quest for both sides which gives good extra exp. You return the artifact, then kill the monk to take it back and tell the cave ghost he's free (if I remember correctly). That shouldn't get you to 7 though, so probably some random encounters were involved, or maybe the guy killed Virgil too. You can actually complete both sides of the bank robbery quest in Shrouded Hills also, if done correctly.