Main skills would be Looting, Inventory Management, and Prisoner Management since you mentioned slave-trading. Raiding villages won't yield any prisoners, so the last one isn't necessary unless you're also going after traveling villagers or other groups as Adorno said (in which case I'd suggest making
this game tweak, maybe
this one too). Of the first two skills I'd suggest focusing a little more on Inventory Management since villages will yield lots of loot, and the benefit of the Looting skill was never as immediately noticeable to me. Others might also suggest the Trade skill but in my experience I barely ever noticed any benefit from it, your experience may differ but I'd say just grab a party member for that.
As for character creation there's a couple or so choices that start you off with maybe a couple points in both Looting and Inventory Management, but it may be better to make a character with a high Intelligence attribute and then spend those extra skill points bumping those two skills. Going with high Intelligence would also give you a higher starting cap for those two.
You probably won't have enough inventory space to fully loot more than one village at a time, even at higher skill levels from what I remember, so just sell everything off at the nearest town. If that town belongs to the same faction as the village you just raided then just sneak in. If the goods merchant has no more money to buy your stuff then just sell to the armor, weapons, or horse merchants, they all pay the same. I'll also suggest
this tweak for cattle movement otherwise it's too much of a hassle getting them to move around.