I would start dirt cheap and gradually inch up your prices when you've built up a reputation. The internet is an international market. In some countries, a little money goes much further, so keep in mind you're competing with those artists too. I once accidentally paid an artist in pesos because that's the currency where they live, but the stated prices were in USD. Anyway, I redid the transaction and it all worked out.
You might start with an "introductory offer" and then do an occasional "limited-time offer" if business is slow.
Some customers want speed. Estimate your turnaround time for a project a little higher and make sure to deliver a little early, and that will help build your reputation. Also be sure to close commissions if your queue gets too long to keep up with.
That reminds me . . . there are two artists I paid months ago who still haven't delivered. One isn't responding to communication at all, and the other . . . maybe it's time to give another nudge.