LvL 1-5 quests, Lannergar mine, wolf pelts
LvL 5-10 quests + selling (bad/useless) quest reward items, killing Outlaws arround Freetown
LvL 10+ Outlaws arround Freetown (Bows + Emeralds), Mausoleum
LvL 20+ no idea, but Mausoleum can get you up to 10k, usually ~5k
For Mausoleum, just get high...