Meltproof makeup.(BEAUTY BOOK)

You don't have to be a math whiz to wrap your head around this equation: The less makeup you use, the less likely it is to run down your chin by lunch. We're not suggesting you go completely bare-faced, but swipe on several thin layers of makeup (whether tinted moisturizer, eye shadow, or blush) instead of one thick one; you won't use as much. Other ways to avoid a meltdown:

Soak Up Surface Shine ...

When your face starts to look slick, cut the grease without caking on heavy powder. Throw a pack of blotting tissues in your purse (in a pinch, use a toilet-seat cover--it works!). Or try Clarins Shine Stopper Compact, $29 (below). It combines oil-absorbing zinc and pore-clearing salicylic acid. Best of all, it's completely transparent, so even if you use it throughout the day, you won't look like you dipped your face in powdered sugar by 4 p.m.

... But Don't Drive Yourself Crazy Over a Little Glisten

Your skin will never be perfectly matte in mid-August. "Use a bit of shine to your advantage," says Vanessa Minnillo, who has managed to look flawless on many a summertime red carpet and recently created a makeup collection for Flirt! "Instead of fighting it too hard, I go for that shimmer-and-glow look by swiping on a little highlighter along my cheekbones and a rosy cream blush on the apples of my cheeks."

Back Off on the Base

For an even skin tone that looks great on its own (like Cameron's), apply a self-tanner daily. Jergens Natural Glow Face Daily Moisturizer with SPF 20. $6.99, builds a subtle, flaw-softening bronze tint. Need more coverage? Just pat concealer on areas where you have redness, like under your eyes or around your nose. (Look for a formula with a dry texture, and use a small brush to apply it; you could overdo it if you use your fingers.)