I'm not a professional artist. I don't feel nearly good enough to be one. I'm a professional author, but I use art to relax and have fun. If I have full ownership of the source of a piece, given I paint from photographs, I may put it up as a print, but I really don't expect anyone to buy one.
I use Photoshop CS5 and a wacom cintiq tablet to create my art. I mostly try to create images that remind me of oil paintings. How well I manage that is another matter.