Tips and Techniques
MAKE-UP REMOVAL: the easiest way is with baby oil or oil-based make-up remover. Dab some on cotton ball and wipe over makeup before washing face. This works great for oil-based make-up like lipstick, which can be difficult to remove with just soap and water.
HOT GLUE GUN: if you don't have time to sew a costume - or you just don't know how to sew - a hot glue gun can come in handy. If you're careful, you can put together almost any costume with a glue gun and skip the sewing entirely, not to mention save a lot of time. Hot glue guns can usually be found at home improvement or craft stores, with many models costing less than $20.
BULLET HOLES: mix flour and water to make a paste and smear it where you want the bullet holes to be. Next, use some make-up to make the past look flesh colored. Then use a pinhead or some other small object to carve out holes in the paste and color in the holes with black eyeliner. Finally, add some fake blood around and dripping out out of the holes and then you're done. Note: you can also make scars this way.
BLOOD: get some clear corn syrup (available at most grocery stores) and add red food coloring to it until you achieve the desired color and consistency for your costume needs. The mixture can be diluted with water if it's too thick for what you want to use it for. This mixture can be put in the mouth or even swallowed, but do not get it in your eyes since that could cause infection. Also be warned, red food coloring can stain skin and clothes.
SCARS: in small container or bowl, mix one teaspoon or one packet Knox gelatin with one tablespoon hot water (careful not to burn yourself). Then spread the mixture on your skin to create scars, burns, or whatever effect you want. Then use make-up, Halloween paint, etc, to color the gel as you'd like and brush baby powder on it with a cotton ball to set the color.
SCARS II: go to a costume store and get Spirit Gum, Nose Wax (putty), and liquid latex. Apply Spirit Gum to area you want a scar, cut, lump, etc. Shape wax to fit your purpose and then press into Spirit Gum (allow spirit gum get tacky/sticky first). You can make incisions in the wax for cuts. Brush latex over the scar and allow to dry. Cover scar with make-up to make it flesh colored. Apply fake blood to cuts and use make-up to color bruises and scars. NOTE: Spirit Gum is known to cause allergies in some people, so be careful.
BOOKS: there are books on how to do great Halloween and costume make-up, like Dick Smith's "Do-It-Yourself Monster Make-Up Handbook." Visit your local library or book store to check their selection and get some great ideas and tips.