I colored Feanix in Photoshop, and here are the main stages of her development process. The final picture has 15 layers (low for most of the pictures I do - Light, Dark, and Laser each have about 35).
1) The original sketch is scanned in (yes, I did it in blue pallpoint pen).
2) I adjusted the color of the ink, and then added three layers, one each for skin, hair, and nails.
3) With preserve transparency on, the skin is painted with highlights and shadows. I also used filters to give the hair a more natural look.
4) I continued working on the hair and nails, and colored the horn, eyes, and teeth on a new layer. Then I gave her a drop shadow for fun.
5) A shine is drawn over the horn and a fire background is added using Eye Candy's fire filter.
6) Finally, more fire is added to the hands, and fire is copied over her rear leg to place her in the fire.