So, you launched the game, and now you think what to choose - what difficulty level and experience system?
First - pick Normal. Play it untill you feel that it's too easy for you, and doesn't have any challange for you.
Then you can start on Hard. When you feel your build is powerful enough to get you bored - then and only then it's time for Dominating.
Don't be afraid to do your own build on Normal - you can finish the game with every build there, even with very non-perfect or straight bad.
Classic or Oddity?
Try Oddity - it's new, you could try classic experience system in every other game.
Oddity has many advantages - did you ever gat that feeling, you met that NPC, done quest for him, and now he's leaving the map, walking to the exit to vanish forever, and he has tons of exp inside of him? But you like him! And roleplay! But exp!
*kill crash murderhoboing*
Or have you ever dropped the key to the door, so you can just lockpick it and get that sweet exp?
Sadly, I'm familiar with such stupid behavior.
But Oddity solves it all! At least for exp reasons.
You don't need to eliminate every single living being in a rush for exp.
Also, you wan't to avoid combat - Oddity is best way to get experience.
And with classic system you will hit the lvl cap long before the endgame... so your character won't develop farther and that's a bit boring - or a lot, while Oddity is adjusted in a way that all fights will be more or less challanging for you.
If you don't have idea how to build a character but don't want to spoil the fun with guides - just specialize.
Specialize in everything - ability points aka stats, skills, feats. Don't be "... of all trades master of none".
Your stats are maximal or minimal, and don't just add stats just in case - they are there to open access to feats and enchance your skills.
Hope it will be helpful for someone.