For Might & Magic 2:
* The starting party isn't that great. Specifically, it's too male heavy (in a game where that actually matters, as some enemies have gendered physical immunity), and the Cleric is too slow, meaning he won't have a chance to cast a spell like Bless before he's constantly busy bringing back characters from 0 HP.
* To solve the first issue, replace the Paladin with a female Paladin. This gives you somebody who can attack those male-immune enemies that crop up every now and then.
* Then, replace the Cleric with one with a female Cleric with 19 Speed. This gives you somebody who can cast a spell like Bless or Holy Bonus before you start having to constantly heal. For a reason that will be apparent later, you want your Cleric and Paladin to be the same sex.
* When you get a permanent stat boost, the current value of the stat doesn't change immediately. To see the change, you need to either rest or fight a battle, then the change will show up. This also applies to a certain other thing that I will warn you about in the next point.
* Do not steal Murray's treasure. (It's behind a door that says "Murray Only". If you see this, turn back.) If you still want to do so anyway, before you go to the inn (which saves the game) rest, then check your stats, and you'll see why I've warned you.
* There's one quest that can only be completed by doing something that feels like an exploit.
Might & Magic 3-5:
* These games all have similar mechanics, so advice that works in one of these games will work in the others.
* MM3's default party is missing a druid, and you actually need a druid or ranger to cast Walk on Water, a rather important spell in a world that consists of islands. So, you'll need to create one or rely on hirelings. Note that a ranger is good enough for this purpose. (Note that this does not apply to Xeen; Druid/Ranger do not have any unique spells there.)
* For Xeen, you absolutely *need* a Sorcerer or Archer, unless you are willing to rely on random charged item drops. Teleport is required in MM4, and Jump in MM5.
* Speaking of which, Teleport works almost everywhere in MM4, but in MM5, it fails in most areas; the notable exceptions are the overworld and the skyroad.
* Knights and Barbarians have significantly higher accuracy than other characters; this makes a huge difference at higher levels in some areas (thinking of a certain Minotaur infested dungeon here).
* If you don't want MM4 to be too easy, avoid using any of the pyramids. Using one of them will take you to MM5, where XP rewards, even from simple quests, are huge, and that will make MM4 too easy. Maybe try the pytamids once you've defeated Lord Xeen and seen the ending. (When MM4 was originally released, these pyramids would just display some message about something not being aligned; it's not until MM5 came out that the pyramids could do something, and only if both games were installed on the same system.)
* Only enemy attacks that do damage can cause status effects (this includes things like instant death and equipment breaking); if you can reduce the damage you take to 0 (via Power Shield or Protection from Elements), you'll also prevent the status ailment. There's some situations (think Liches, for example) where this makes a huge difference.
* Holy Bonus drastically increases damage at higher levels; Heroism only increases accuracy, but sometimes that's what you need.
* AC only matters in areas where enemies use physical attacks. In areas where enemies don't, you might want to unequip your armor so it doesn't break if you get down to -10 HP. (These days, I actually don't bother with armor in the Xeen games.)
* Save early and often; you never know when something will go badly, like having somebody killed as the result of an action.
* There's a bug with some permanent stat boosts, particularly in MM5. In many cases, if you check a potion, then cancel out of using it, it still counts as a use.
* Don't play Swords of Xeen until you've played World of Xeen. If you do decide to play SoX, consider that it's basically a mod of WoX that somehow got a commercial release. It has a lot of scripting bugs in it, and is sometimes unbalanced. Play on Adventurer difficulty, not Warrior. (This is in contrast to WoX, which feels decent on Warrior difficulty.) Also, Clairvoyance is unreliable in SoX.
JoeMD: Can anyone recommend a guide/ mod/ way of playing to make things a little easier? I know I'll probably get a lot of stick for this, but I do find it rather overwhelming. I'm not terribly young (40 next year) but my firs RPG was in the 16-bit console era and those weren't as grandiose as M&M.
brozo: My advice would be to play VI and ignore I to V. They are just too old to bother with.
I highly disagree with this. The earlier MM games are quite good.