Adam Huber is the creator of Bug, which for my money is the most consistently funny gag comic on the internets, and today he looks back on what he has learned during the first year of his webcomic. His advice is concise and useful for beginning creators: Accept that you're going to make mistakes, switch to something else if you hate what you're doing, prepare to give up some of your free time, and don't forget to lawyer up:
At some point, once you feel you got a handle on your comic and it’s cast of characters, go find a lawyer and make sure your comic is not infringing on someone’s already established property. The lawyer I saw charged $100 just for a meeting but it was money well spent. I learned a lot. You don’t want to get hit with a cease & desist letter from a company with deeper pockets than yours.