Ok, so, extending my explanation from before about the layers.
As LM said, once you have your sketch done, you put the base colours (also, as she said, I recommend to do every section in different layers, so, for example, you can have, skin, hair, clothes, etc etc) in each layer. Don’t worry about adding any depth at this point.
After you have all the basic colours done, let’s assume you want to do the shadows of the hair. So, what you want to do here, is.
- Create a layer on top of your hair colour one.
- Next, choose a cool colour I usually use an almost white blue. Really, is like really really reeeeeeeeeeeeally pale.
- Now, with this layer you have created, you need to set it to multiply.
- With your cool colour and whatever brush you like to use (I like one of the soft ones, since it makes a better blending effect), paint in the places you like to put the shadows. Since the setting of this layer is in overlay, you will see instant shadows. If it’s too dark, do not worry, finish all the shadows, and then play around with the opacity, this way you can make your shadows softer as you please.
- Done! Your shadows are done
Now, for the highlights, the process is exactly the same except for two things.
- First: When you create the new layer (again, on top of the basic color one) set it to overlay instead of multiply .
- Second: Instead of choosing a cool color, choose a warm one this time. And again, make it rather pale.
- Now you just need to paint in the places you want to have highlights. And you are done!
Same as with the shadows, feel free to play around with the opacity of the layer.
And if you want extra life, then you can manually add touches of colour in certain places (for example traces of a very warm colour to simulate some lose small hairs).
I hope you find it useful