If you just started and you are a beginner, ask some of the people in your group that you start with for money. You might get some copper or perhaps even some gold. Note: This does not work if at a high level.

If you fight skeletons, snakes, giants, and other creatures, you might get some body parts, gems and other items to sell. Gems will give you a lot of money but body parts do not sell for as much.