I gotta disagree. I’m no stranger to all powerful builds, but you really have to thread the needle and ride by on just barely passing a bunch of stat checks and knowing all the right choices to make. For someone starting out and just trying to make it through the game without losing a companion and failing a bunch of checks, they need much less.
Here’s what I’d recommend in loose order of priority:
I’d recommend one combat skill to be high, so you need a high blades, archery, unarmed, or magic. Magic is obviously the most useful, as it manages to count as both a combat skill and a noncombat skill, being both useful in more situations and easier to build up as a result. I find archery the least useful - it really won’t carry you through the final battle in the second book.
Everyone needs charisma. Everyone. It’s just too useful.
Next, building a mid to high agility or strength. You want one of the two. If you’re building a high strength, endurance usually follows. That said, endurance isn’t that useful on its own.
You’ll then want to try to get one of the knowledge stats up. Arcana, nature, and history are all about the same level of easy to raise and about the same level of usefulness. You really only need them up to about 60 to get all the major checks you need with them. Geography’s real rewarding if you can get it up, but it’s also the hardest to raise. Religion isn’t that useful and it’s hard to raise high unless you’re a priest or cleric, or you spend a lot of time training with Peter/Petra. The only real deal with religion is the level 50 (or is it 40? Now that I think about it, I think it’s 40) that you need to make if you want to go into the necromancer prestige class.
And all of these priorities are going to vary a little based on class focus. Thieves are going to end up with high agility, stealth, and devices, which they can use as a bit of a substitute for passing obstacles that you’d need knowledge skills for, for example. Anyone taking a lot of wizard levels is going to have a sky high arcana skill without much effort. And so on.