Like what should my inital stats when I start the game be

it worth considering investing a few points in constitution.

If you don't, you start with 20 HP. For each point until you reach 14 you get 2 extra HP after that you get the normal effect.
So a NO with 9 con starts with 20 HP, 12 con gives 26 HP, 14 -> 30 HP, 15 -> 33 HP, etc

The extra HP you get from raising your con from 9 to 14 are not in the rules book. I don't know if you also get them if you delay raising con.

No, those are not gained retroactively. And, personally, I would disagree with you on them being worth spending points, especially considering TNO's innate HP regeneration. The max amount of extra HP you can get this way is 10 (not counting the regular HP/level bonus from raising Constitution to 15 or above which is retroactive; you start at level 3 instead of 1, which is why 15 Constitution immediately gives 3 extra HP). Ten HP is basically just one Fighter level if you get a good HP roll, so in the long run these are hardly worth potentially missing out on dialogue/quest opportunities as a result of putting less points into mental stats, which have fairly high checks. Unless you're playing solo, which IMO is a sorta... unconventional way of playing PS:T, especially the first time around.

For the record, here's the Constitution/InitialHP chart the game uses (see attachment, because the forum doesn't process spaces correctly).

I usually max Wis and start 14 Con (I like free stuff) and toss the rest in Cha with maybe a few points in Dex/Int
You can easily boost Int with Cranium Rat tails whenever you need high Int so I usually delay putting points in Int.

Well, yeah, I suppose it's possible... if you know when you need high Intelligence. But I'm assuming the OP is a first-time player, judging from the question, so the only way he could pull this off without a walkthrough is chewing on several charms before every conversation. Even the Mortuary has a check for 16 INT (if one wants to get the maximum experience out of those giant skeletons), so if he wants full access to the dialogue, naturally high INT is the way to go.

What about when you get stat points from leveling? Still put them in WIS? Or should they be in the stat of what class you are playing?

In theory, raising Wisdom is always good, no matter your class. In practice, if you start with 18 and manage to get all of the permanent upgrades to it, it'll max out naturally (and you only need 24 of 25 points in it if your aim is to pass all of the dialogue checks). In that case, if you just want the EXP bonus, better just get a +2 WIS tattoo. If you start with a lower value, you can still raise it with a tattoo, so as long as it's not too low, you should be okay.

Raising the class stat: yes, that's the idea, and a major reason why it's convenient to play a mage (since Intelligence is important for dialogue). Fighters get the most useless class stat ever, as Strength only affects damage and weight limit; thieves are a middle ground, because AC bonuses are a good thing, it's just that mages have ways of raising AC to insane values that don't involve spending stat points. You can try to balance out your stats by using tattoos, though, as you can swap them according to your needs. But keep in mind that more powerful tattoos tend to be class-limited.

If you have a build with sufficiently high Intelligence and Wisdom, you can afford putting levelup points into physical stats, but these mostly don't have any effect until they get to 15.

On the topic of dialogue checks, there's also the matter of Charisma. Mages can easily raise it by casting Friends, but for other classes passing later Charisma checks can be tricky. (You could get mage training, switch back to your primary class and have Dak'kon retrain you into a mage whenever you need to cast a spell...)

thanks for the tip. will get those to 25 before messing with others.

Wisdom is pretty much the only stat that becomes more efficient with every point, no matter the value - but the dialogue checks increase gradually, so if it's already high at the start, you won't have to worry about them for quite some time. Same with Charisma. Intelligence is an odd stat in that even for mages it largely stops being useful at 19 (there are higher checks, but there's usually more than one way to pass them), and mages have access to +2 Intelligence tattoos and can raise it via their class bonus.

Also, if you're going to become a mage, you'll have to deal with the fact that they require (initially) more EXP per level, and while the EXP bonus from high Wisdom offsets this to an extent, you'll be spending sufficient time without getting points to spend on your stats. Thieves level the fastest, fighters are a middle ground. Plus, you don't get character points in your new class until you get it a level above your previous classes (so if you want to become a mage or a thief, do it at the first opportunity).

[QUEST SPOILER]

There's a 25 Charisma check mid-game. To be fair, it involves a character who can be a complete pain to find, even if you know he exists. The Friends spell can raise Charisma by 8 points if you're especially lucky, but it's random by default.

[ENDING SPOILER]

If you want to talk the final boss out of fighting you, you'll have to reach him while having either 24 Wisdom, 24 Charisma, or a certain item. Wisdom is easy to get to that value if you know how to get permanent bonuses, or if you keep some tattoos around (you can get +4 Wisdom points just from those). The result of the high-Wisdom route is one of the best bits of dialogue in the game.

On top of this, you're immortal, so combat isn't really something to worry about. Graveyard zerging is a lovely thing :)

There's very few enemies where you can die for real if they defeat you. Take out the ones where you can avoid them through talking with your high mental stats (and the super-powered NPCs that you shouldn't be picking fights with at all), and I think there might be maybe one fight in the whole game that could even pose such a problem (without spoiling story, I'll say it's a mandatory one-on-one fight in one part of the final dungeon).

So yeah, while I did have fun with my Fighter playthrough, the mental stats/dialogue are really the way to go :)

I enjoy playing high STA characters, even though my first and preferred character was, like others said, the classic top WIS, rest between INT/CHA Mage.

Many people complain that the combat parts are difficult, well they are a lot less so when you get +5 free HP on every level and can protect allies with your body (even Mage players). STA affects your regeneration rate too, by the end of one game my 25 STA character with the Lost Incarnation tattoo was healing several hit points per second, ie. could return to full health after battles in real-time.

I could also reach working CHA without ever putting a point into it on the same playthrough:
plastic surgery by Sebastian the mage +2 CHA
relevant tattoo +2CHA
(and you're already at 13, which is the treshold for the easier checks)
and then I just cast the Friendship spell (really huge temporary CHA boost, and you can cast it twice if you want 25 CHA) before critical conversations.

Which, incidentally, appears to be an exploit (it's not supposed to stack, and some of the fan patches fix this).

I believe the complaints about combat are not so much about it being difficult (I mean - you're immortal and can revive you allies) as about it being... well, dull. When 99% of the enemies can be killed by simply bashing them with a weapon or a first-level spell, and very few of them cast magic or any other negative effects at you (so you don't even need resistances or any defensive measures), there really isn't much strategy to battles.