all you do is find customers and they tell you what they want drawn, you draw it, and then scan it and send it to them. and they pay you for it. I ask for about 3k for my drawings but you should ask for more since your a better drawer than me.
to get customers you can make a shop in forums, mini shops, then requests and commissions. you post an introduction, your prices, what you'll draw, if you will color it, etc. you also have to post links to some samples of your drawings.
I sold a couple commissions and its fun! good luck to you! ^_^