The reason your version looks unnatural is because skin consists of more than two tones. It is not uncommon to have upwards of 15 different tones; of course, this can be simplified for more cartoon-like images.
I actually have very little experience with raster programs, but I gave it a shot anyway.
I only used 5 tones (base, 2 shadows, highlight, warmth).
Then I fiddled with the colors to make it blue/dark.
My colors aren't really blended, but you probably get the idea.