Well, that depends to what degree you're willing to go. The easiest is Dwarf Flesh with an Ogryn Flesh wash. You can deepen this by doing layers of Dwarf Flesh over that and leaving the darker color in the recesses:
Or the same process with the darker Tallarn Flesh:
A more complex (and better looking
IMO) method is to do layers. I start with a layer of Dark Flesh, move up to a layer of Vallejo Tan, then finally a layer of Dwarf Flesh, with each layer leaving some paint in the recesses: