CUT FOR SIZE. So here’s what I got on this:
First off the obvious, be aware of your lighting. This is important, since you need to know where highlights and shadows fall. Sometimes, usually with my more ‘painting’ like works I make a little mark as a reminder.
(This little doodle is not a finished piece, usually I’d have this clean before I color but it’s for the sake of lesson.)
My personal method I have one “base” color, and two shades lighter and darker, like so:
(Yes, I draw my character enough to warrant making a basic palette for her; I also share it with other people who would like to draw her.)
Using the base color, you color up everything. (It helps to have it in a layer UNDER the lineart, with the lineart set to ‘Multiply’.
Remove whatever may get ‘out’, by erasing, or selecting the space on the lineart layer, go to Select > Modify >Expand and make it 1or two pixels, and going bac to the color layer and deleting.
There are two methods you can do with the highlights and shadows.
1- Copy the ‘base’ layer and paint over it, and using the Smudge and Blur tools, blend them (what I commonly do)
2- Make a new layer for each color, paint and give it a Gaussian Blur
You could even try a mix of both to get different result. Take your time, do it over if you have to, skin is one of the harder things to color, this is just the ‘simple’ method of mine. Work it until you’re satisfied. Then add in the rest of the colors that might occur once you have the skin down pat.
You can even go in later and set layers of color to different styles to add to the picture and whatnot, but that’s more for after all the colors are done.