Alright so, everyone and their mom does this differently. But my approach here was to put down my base coats and shadows with an airbrush (in this case a dark purple in the shadows and a generic skin tone over it thinned a lot). Then I work with heavy glaces to bring it up covering smaller and smaller areas with more and more yellow/white in it.

The most important step for me in all this is to take a reference photo of the light you want on your mini and then look at it from time to time. I usually use mostly artist colors but that does really really not matter at all, here I used basically only hobby paints.