To protect skin and ensure the foundation's even application, apply moisturizer to your face before foundation. Let it absorb into your skin for a few minutes before applying foundation. This way your stage makeup will sit on top of your skin and not flake. Choose a foundation a bit darker than your own skin tone, especially in a larger theater, as lights in these venues tend to wash out the face more.
Since harsh stage lighting often changes the appearance of certain colors, you might want to substitute these colors. White makeup often appears blue, so cream colors should be used instead. Blue and purple may appear black. Substitute them with brown shades. Yellow may also appear white under certain light. Compensate for this by substituting it with reds, pinks and oranges.
There are several tricks to change or bring out your facial features. To reduce fullness in the face, draw a shadow line on the jawline from one ear to the other. To accentuate eyes, use a cream eyeliner on the bottom inner sockets. This will create a heightened contrast with the brown eyeliner you use and make the eyes appear larger. You can also use a pale cream eyeshadow (powders have less intense color) on the eyelid, applying a dab of shimmer in the center. Avoid over-shading the nose area, as it may be too prominent onstage. For unmade-up lips, use dark red lipstick. Its appearance changes under stage lights.
To prevent makeup from running due to excess sweat, use water-resistant products. These won't be water-based and are often called grease paints. You can also also use setting powder (which should actually always be used) and certain waterproof seals or topcoats available at various stage makeup suppliers. For men's stage makeup, all contouring should remain the same, but men rarely need false eyelashes, and their lipstick colors should be more neutral.
There are some common mistakes you should avoid. Line the eyes with brown rather than solid black liner. Black will actually make the eyes look smaller. If you do use black, mix it with brown. Avoid foundation that is too dark. As stated above, foundation shade depends on the size of the theater. Ask someone observing makeup rehearsals to assess your shade. Avoid oily, shiny foundation. Apply blush on the cheek hollow rather than the apple, and don't forget to define your eyebrows.