Selling slaves is always good. Oh but...I can't find the SODDING SLAVERS!!!
(someone find a fix,please!)
sorry for the rant....a good tip at the beginning is to head for Khudan and buy all the furs there, as they are usually priced at 50 and can be sold at lots of places for 300+ each. It replenishes after a while so I always check if I'm in the neighbourhood.
And hanging around Tihr and bashing sea raiders with blunt objects is good to, as Ramun the slave trader is always at Tihr.(sea raiders=50each, I think).
This is a good strategy as it levels you up as well as raking in loot to sell or equip your companions with.(but you need Slavers for this!!!grumble)
I always keep a slaver army, and take it out for a run when I need to raise some cash. Obviously save your blunt-weapon guys for slaving, don't waste them in sieges and such