Once I get some free time (and maybe the minis to practice on) I was going to post an article about "fantasy" type skintones, and I had a couple ideas for undead skin. First, there's the pale, blood drained corpse which is good for vamps, but maybe even zombies for contrast. This can be done by mixing a light blue grey with a pale skin color of your choice. Next, the petulance look can be achieved by blending in patches of red with yellow dots. The classic zombie look will usually be a greyish or unsaturated blue or green look- and if you go a bit darker you can put some bright yellow-green bleeding out from the eyes, mouth and other orifices of the toxic zombie for a good look. Possibilities are endless for undead flesh- just make sure it has an unsaturated look to it- as far as I know, there are no hot pink zombies running around in any media.
Hope this helps get you started in the right direction!
