Super simple&fast coloring tutorial.
Warm red chromatic scheme added
Duplicate character layer and set shadow color. For speed and simplicity sake, I used ctrl+U (Hue & Saturation) and just dragged the hue slider over, as well as lowering the saturation a bit.
Add a mask to the shadow color layer, mask out light areas.
Added a bit of color in the background.
more of the last step, + some detail. Here you can even out chroma if something looks off as well.