Difficutly uses the same formula in single player. power draw for bows, power throw for throwing weapons and STR for armor, melee and crossbow. Another thing is the slot system. You'll figure it out, if you monkey with it a bit. Another thing is, always ask for help or check some guides when building your character. Otherwise, you'll get a useless character after lots of effort. Go and read 5-6 guides. It is something you know already, but in a bit different game dynamics.
Also: Never go for ranged first, it is frustrating compared to native. The reason for this is there are lots of whiny twohander/polearmers like rufio playing this game, and devs should keep them happy.
Edit: I meant, the ranged is frustratingly useless compared to native and even Vikingr.