I have been playing with this little chap in my spare time at work....and I went for a "Marble" effect base, the Macro on my camera is vicious and shows every micron of paint out of place, it looks better in real life, you are probably seeing this 5x bigger than it is - depending on your monitor, but to do this easy, paint white, then a thin irregular line of bleached bone...then wash to one side with water to leech the colour out, then an even thinner irregular line of scorched brown, and again leach out the same way, then a coat of "ardcoat"
He is very much a work in progress.