I use the same colors and procedure for painting skin as Jaume Ortiz. That's to say, I like his colors, the method makes sense, but I make no pretense of being as awesome a painter as he is. Still, one tries...

Basic skintone is Vallejo 876, Brown Sand. In the photo below the model's received two thinned coats.

First highlight is Brown Sand mixed with Basic Skintone (Vallejo 815) in a 3:1 ratio, thinned down of course. I wonder if I thinned it a bit too much. Oh well, nothing that can't be fixed later.

Second highlight is the same as above in a 2:1 ratio, applied within the areas of the first highlight. The third highlight goes only on those bits that naturally catch the most light and consists of the same colors in a 1:3 ratio. In the photo below the second and third highlights have been painted on. Shadows next!