Mix shortening and food coloring in a small bowl. The amount you use depends on how many faces you'll be making up, but no more than a spoonful or two will be necessary at a time. The shortening spreads well and goes a long way. The food coloring can be any color you like, depending upon the effect you're after. Mix the food coloring with the shortening to color it. If, for instance you need to create makeup for a Martian, you'd mix green food coloring with the shortening as your base. Add a small amount of cornstarch to the shortening or apply the cornstarch to your face before applying it. This helps keep the shortening from smearing.
Create textured facial makeup by adding oatmeal to the shortening and food coloring mix. You can also create scars by adding a small amount (just enough to moisten) of water to raw oatmeal. Mix well in a small bowl. Add drops of red food coloring to the oatmeal and water mixture to give the scar the proper coloring.
Pour corn syrup into a bowl and add red food coloring to make homemade blood. Add two or three drops of red food coloring to start off. Continue to add the food coloring until you achieve the color you're after.
Experiment with mixing various food coloring to create custom colors for your makeup or by adding various textural components, such as a glitter for a sparkly effect.
Create dirty-face effects with standard charcoal used for a barbecue grill. Wipe the charcoal across your face and smudge it with your fingers for an authentic grimy face. You can also use standard chalk in different colors for eye shadow.