I should have taken pictures of the step-by-step process, but it's pretty easy (this was my first time).
First I put a thin layer of elmers glue on my chest..then covered it with toilet paper.. I made it uneven to look more realistic. Make then I applied another layer of glue to wear I wanted it to lay down more...and to the edges to blend the toilet paper in with ur skin.
Wait for it to dry..
Next I put white and black Halloween make on my skin to give it a grayish zombie color...make it a little darker around the edges...I covered the wound edges with makeup and blended it in...for the wound I added some black makeup for shading then covered the whole thing with fake blood..then added in more black.. I caked on the blood in a few spots...it will also most likely stay a little sticky, depending on what kind of blood you use.
This was a lot easier than I expected...it could be better..but pretty darn good for a first attempt :). Have fun
This first picture is before it was blended good and still a little wet..
Here's the finished product..