The basecoat for the model is a mix of Chaos Black and Red Gore. I probably used three or four coats of quite-watered-down color to give a bold enough coat, without the crimples and visible brushstrokes that you get from using paint that is too thick.
Then comes the laborious task of highlighting all the skin up from this very dark color. Obviously I could have started lighter, but I think this loses something… Plus, you don't want realism, do you? It is a high fantasy model, after all. The first couple of highlight shades are just the basecoat with more Red Gore added. Until you get to Red Gore itself.
Next, Blood Red is added to Red Gore - at this point, I'm probably painting about half of the surface area of the skin. There are three highlight stages between Red Gore and Blood Red.
The final stages are Blood Red mixed with Fiery Orange. Then Fiery Orange by itself, and lastly, Fiery Orange mixed with Skull White. These lighter colors are painted (very carefully) in lines along the raised areas and in the center of the muscles. I tried to use tiny lines as much as possible and avoid dots. This was to give a kind of 'grain' to the muscles, as well as to accentuate them.
I didn't paint all the skin at once on this model. I did the head first, then the rest of the body later. Too much like hard work otherwise, and the paintjob will suffer for it.
Photo blocked by adult filter:
"Bugharoth's skin is finished"