I've had a lot of free time lately, so I decided to fill it by coloring some of Jack's pinup. I did a fairly simple one a while back with a Sin City theme and decided to raise the bar a bit with this last one.
The secret seems to be layers, layers, and more layers. Oh and the Hue/Saturation tool.
I personally like the first one the best. The last one is a little meh, but it was more of a color experiment than anything else.