I am using Fractal Design Painter and Paint Shop 3, but you could use
any art program or your traditional colors on paper or canvas
I am going to use this black and white photo of the model..
I begin by drawing the red lines of the edges and filling the background
I paint a few flesh tones and greens in the eye

See how i use green and blue tones for the flesh color
The final picture, klick on it to see
it bigger