What Style of Head? I'm assuming P1 by the way you referenced the head color being yellow.
Also is it a Resin Bust or a Latex Display Mask?
Xterminatus does an amazing walk through of painting a P2 Head, and he outlines the colors he uses each step of the way.
http://www.thehunterslair.com/index.php?showtopic=17808
I've seen many people mention the colors they use on their masks, but I don't remember what they were off hand. I'm sure somebody will chime in. If not, spend sometime searching, you'll find what others use somewhere.