This is from a little article, about homemade zombie costume ideas, I found at ehow.com by Timothy Sexton. Enjoy:
According to lore, zombies are the dead that rise from their graves. As a result, most zombies are rather nicely dressed since most people aren't placed into a coffin wearing jeans and a T-shirt. Of course, most zombies appear to have been buried for some time, so you might not want to wear your best suit. If you can find an old suit no longer being worn, all the better. If you don't have access to formal clothes, create a backstory for your zombie of being buried in the clothes you were wearing at the time of death.
Again, it is important to remember that most zombies were prepared for burial by a funeral director. As a result, your skin should look a little unnatural. One way to pull this off is by first covering your face in white powder and then applying flesh-colored makeup as well as a very light covering of lipstick. Or you can simply go for the effect of having been buried and not being exposed to the sun for awhile and make your skin very pale. You can give yourself an eerie pallor by covering your face with glow-in-the-dark makeup.
Make realistic rotting flesh at home using simple oatmeal. Just mix enough oatmeal in water until you've created a paste. Apply the paste to your skin and put some makeup over it to match your skin color. As the paste dries, it will begin to flake off and look like skin that has rotted and is starting to peel away from the bone.
Smell of Decomposition
One essential element often overlooked when making a zombie costume is the smell. After all, being buried is bound to make you smell pretty bad by the time life has been breathed back into your body. The best way to make sure you smell like the living dead is to rub your costume with the world's stinkiest cheese: Limburger.
You should definitely pepper your costume with dirt and grass to reveal what it's like for a zombie to climb up from six feet under. You might even want to mix some corn syrup and red food coloring to create the effect of bloody fingernails that would probably result from clawing your way out of a coffin."
Zombiethon is a community FUN run/walk event held on Halloween, Saturday October 31, 2009, from 4-6pm, along the recreation trail around Silver Lake Reservoir in Los Angeles, California. This event is organized to raise donations for Brain Cancer Research. All of the proceeds will be donated to the local charity, City of Hope, to find a cure for this devastating disease. Your $10 donation will grant you a numbered participation bib and goodie bag! This is a family-friendly event, and everyone is encouraged to arrive in their finest zombie attire. If you don’t have access to zombie make-ups, don’t worry, for an additional donation of $5, you may have your make-up applied by professional special effects make-up artists on site! Not a runner? Don't worry! It's not a formal race, just a chance for everyone to get out there and have some fun while supporting a very important cause! Hope to see you all there!