A simple idea where you desaturate part of the picture and make it look as though you are painting colour onto it.
I set the Olympus E-P2 camera up on a tripod and on the two second delay. Positioned the left hand in shot so the camera could focus on the correct position and then pressed the shutter and moved my right hand in to place to do the painting.
I then opened the photo in Photoshop duplicated the layer, created a layer mask on the duplicate. Desaturated the layer and then erased the mask so the colour layer below showed through in the necessary areas. I used a brush with a rough edge to paint the mask away so it looked more like paint.
I also selected the skin colour as the brush paint colour and painted that onto the bristles of the brush so it looked like it was loaded with paint.