yeah, i think that jamescuk is nearly right. id do this;
1) start with a tanned flesh basecoat
2) paint over completely with dwarf flesh so you cant see any of the basecoat.
3) highlight the raised areas of the face with a mix of elf and dwarf flesh 1:1
4) 2nd highlight of elf flesh
5) 3rd highlight of elf flesh and bleached bone. i find bone makes it look less chalky that white.
6) very very very watered down brown ink wash, mixed with a little pva glue.
7) paint eyes and teeth etc.
hope this helps. sorry about all the flesh colours but i think that a 'meduim flesh colour' will mean something different to everyone.