Flesh tends to get large areas of purples & reds were blood has pooled after an individual dies. Also, yellow is an appropriate color, skin tends to get yellowy after a bit. Green's good for areas of rot. Greys & whites is your zed's got an ashy long bled-out look. Of course spatterings of reds for blood; I like a mixture of brights & maroons. An overall black-wash tends to bring out details as well. It's pretty much a trial & error process till you get the look you like.