Getting ready for summer involves more than just spending hours on the elliptical machine. To look your best, you also need to sweatproof your beauty routine. Even though the warmer temps and the sun can make you feel great, they can also wreak havoc on your skin and hair (wrinkles, skin—you name it). And does anyone need the raccoon eyes that show up when their makeup melts on a humid afternoon? In order to help you adjust to the sunshine, we've asked beauty experts (who've worked with everyone from Madonna to Halle Berry to Fergie) to share their secrets on how they keep their celebrity clients looking fresh in the summer heat.