Help With Commissions?

Hey guys! So the other day, a fellow deviant requested that I do a piece of art for him, and he offered to award me some points for it. This is the first time I've ever been offered a commission, and it got me thinking: There is something that I really want to raise money for. And what better way to do it than by doing the things that I love, like art? So I'm considering opening the possibility for people to request commissions...but unfortunately, I'm a bit of an amateur when it comes to that. I was wondering if people could give me suggestions on how to go about doing this? If so, it would be greatly appreciated!