I have no idea about how commisions are priced in Rescreatu, so I can only give you advice:
I don't think you're ready for selling your art quite yet. It's not the transition between traditional to digital that I'm concerned about - it's the transition from 'formlessness' to a reasonable understanding of anatomy.
Pencil and paper and GIMP are only mediums - they don't give you skill, they just are a canvas for you to work on and display your own skill. Up your skill levels.
tle="this page">http://alexhays.com/loomis/ has amazing tutorials on just that - upping your skill levels.
It focuses on humans and things though.