For this makeup you'll need:
-an eyeshadow pallet
-red and green food coloring
Step 1: The Base
Peel apart 1 ply from a tissue, and rip it into a piece the size of the palm of your hand. This will be a large rot/wound area. Apply a layer of glue to where you're going to apply it. When it's on your face, bunch it to look like peely, rotten flesh. Go over the edges of it with the gluey q-tip to make sure the edges stick to the face.
Once all that is dry-ish, go over your whole face with foundation (powder will probably work better). Don't forget to pale your lips!
For the smaller rot/wounds without tissue, use tweezers to peel a hole or two in the middle of the glue, to give the appearance of a hole in the skin.
*N.B.- Really make sue you stick the edges to your skin. Other wise it won't blend in.
Step 2: Eyeshadow Everywhere
Temples: Brush purple and black into the temples, and go around that with yellow and green.
Nose: Again, a bruised look. Brush the sides of the nose with a dark purple, and blend outwards with your fingers. Brush a mix of brown, yellow, and green down the center of th nose.
Big rot/wounds:Start by brushing black in the center of the wound. Ring around that with purple, then yellow, then green, orange, then a brownish green, blending into your skin.
Small rot/wounds: In the holes, brush black with a small brush. Use orange or purple around the edges of the holes, and use green and brown to blend the edges into the skin.
Step 3: Veins
Step 4: Blood
For a quick and easy fake blood, mix about a tablespoon of honey with 5 drops of red food dye and 1 drop of green. Add 1 tsp of cocoa powder.
To apply, just dip your fingers in and go crazy! It's best to just put it around your mouth, where the blood would be if you were to take a bite out of someone.
Also, dab some into the holes of the smaller rot/wounds.
To make your teeth nasty and zombie-like, put black lipstick or eyeliner between your teeth, and smear yellow food dye on your teeth with a q-tip.
That's about all! Tweak your makeup until you're satisfied, then go out there and munch some brains!