Older piece I did for fun. Tried a slightly different style from what I usually do. Also documented my process!
Initial sketch. I sketch the face and body shape first (blue) then drew the clothing over it on a new layer (green). Then I drew the gun on yet another layer (red).
I flatten and then turn the opacity down on the sketch, and do some clean line work on a new layer.
Now the sketch layer is turned off, and I paint in the color flats on a layer beneath the clean line work.
I then build up highlights, shadows, and rim lighting on clipping masks attached to the flats layer. Done!