That's a nice looking print...
Very nice!
I have to say, I believe your customs have the best skin tones. Very realistic.
Are you using some technique like glazing when you apply the layers on top of each other?
Here's a link to a Citadel painting tutorial video that came with the new $100 book or something like that. It's over an hour long but it has some good stuff in it.
http://www.youtube.com/watch?v=Y1Ev_qLJkxw