>>1518541As another sans Photoshop, I empathise.
I use magic wand to select the area I want to colour differently, create a new layer and fill the selection with the colour I want (you'll usually miss some pieces here and there, and that's when meticulous use of the paintbrush comes in. You can achieve different shades by changing the blends on seperate layers, such as using "multiply" or "lighten" rather than normal, and by fiddling with the Curves. I can't give you any specific numbers; you'll have to experiment with each picture.
