It's been so long since I played I can't even remember what I concentrated in. I can tell you two things. One skill you need is lockpicking. Keep that sucker maxed out whenever you can. It drove me nuts when I couldn't open a chest. The other skill you don't need is summon vermin. I had such high hopes for that skill and it sucked big time.

Here is a lot of information on Divine Divinity from The Locus Inn part of this website I believe Mythros made it. Don't quote me on that, but I know he is a huge Divine Divinity fan.