Like any canvas, your face needs to be primed before it's painted. That's what a good foundation does. "It preps your face, balancing and evening out your skin tone," says Alison Raffaele, a New York makeup artist. "And that makes everything on top of the base last longer." More foundation facts: Artificial lighting can be unforgiving, so unless you've got a perfect complexion, you'll want a photo finish that only a makeup base can provide. Another camera caveat: Avoid dewy products that will show up as shine.