This video tutorial explains how I color and shade my Sugimori-style fakemon artwork (using Serpecidus as an example). I do most of my fakemon art in Photoshop, but the steps involved should be easily transferable to most other art programs with layers (GIMP, Paint.NET, maybe FireAlpaca or something, etc.; I have used GIMP and achieved identical results before, for example). It's a bit long and a hair outdated at this point, and it's done a little clumsily since it was my first time recording anything like this, but it should still be useful. Enjoy!
I may do another, more refined version at some point in the future. We'll see.
The video is pretty large, so you may need to wait a while for it to load if this is your first time visiting the page.