With white paint sketch the zombie mouth. Then take bright red mixed with white and paint the veins. Use white paint for teeth. Deepen the mouth with black and red.

Cover your eyebrows and apply bright red mixed with black to your eyes, nose and forehead. 

Use bright red to draw small veins. Blend the teeth. Apply more white to the places you want to brighten up. When you are satisfied with your shading apply fake blood all over your hands and neck. Now you are ready to go!