Here's how we did it.
Start with liquid latex. It's kind of as gross as it sounds. And it smells. But it's worth it.
Paint it in layers on in the areas you want to have a wound. Dry it on a cool setting with a hair dryer.
Then using tweezers, pull it up and rip a hole in it. This is the wound.
Using "blood" paint, make the wounds. Paint the inside of the hole and add globs in there. Clots look good.
Using white theatrical paint and a make up sponge, pale out your subject. Then add dark eye shadow around the eyes and on the cheek bones to hollow out the cheeks.
For lips, you can use an eyeliner pencil, lipstick or leave them alone. My kids didn't love the first two choices so we left them alone.
Voila. You have creepy.