What you'll need:
Halloween face paint/makeup
1. Get some old clothes and rip them up. Get a good pair of scissors and cut some holes in those pants and make some rips in your shirt. Use a small knife on any tough material like jeans. If you don't want to use any of your old clothes then take a trip to your local thrift/second hand store.
2.You'll want to get some of those Halloween face paints you see in stores this time of year (if not you can always just use normal makeup) You'll want to get some black and white paints. You'll want to start out with a layer of white makeup on your face, don't forget to put makeup on any exposed skin too. (arms, hands, neck, legs etc.) Then you'll want to blend (using your fingers, a sponge or a tissue) in some black, careful don't use too much black, start off with a very small amount. Blend it all together and get the shade of grey desired. Pay special attention to the eyes, you'll want to add a darker layer of grey around your eyes.
3. Grab a handful of baby powder or flour and rub it all in your hair. This will make you look even dirtier and like you came from under the ground. This looks best with darker hair. Rub in as much or as little as you want. If you'd like, put some on your face and clothes too.
4. Now for the most fun part and most messiest! Get your fake blood out go nuts. You'll want to put the most amount on and around your face. Some blood on the corners of your mouth, under your nose, coming from your hair line, and maybe even under your eyes. (Careful to not get any in your eyes or mouth.) Don't forget to put some blood on your clothes too. Smear it, splash it and drip it on your clothes for different effects.
5. Now that you look like a zombie, it's time to start acting like one. Start practicing that stiff-leg-walk. Zombies are very slow, so don't move too fast. Get a good stare-face going and blink as little as possible. Don't forget your moans. Like the moans you used to hear in school when your teacher said there was a test tomorrow, and the whole class would moan. (well, maybe you still hear that if you're still in school.)
> Add some small amounts of green face paint to your skin to give it that extra rotting look.
>Instead of putting flour or baby powder in your hair, try oatmeal. If you're using very liquid-y face paints, you can put some on your face with the paint to give your face more texture.
>Don't forget to tease your hair a bit for a messier look.
> Be careful about putting face paint and fake blood around your eyes and mouth. Even if they say it's non toxic, that shit stings and will make your eyes water.