Even hair that's perfectly obedient the rest of the year can mutiny on a summer day. As moisture in the air permeates the hair strands, they expand...and expand...and suddenly the style you left the house with has tripled in size. Start controlling the situation in the shower. Shampoos and conditioners that contain lightweight silicones help lock down the cuticle of each strand, blocking moisture from entering. (Try Herbal Essences Touchably Smooth Shampoo, and Nexxus Hydra Sleek Silken Smoothing Conditioner.) Continue the cuticle-coating process after you shower: When hair is still very wet, comb through a silicone serum from root to tip (a dime-sized dollop should do). To fight frizz in very curly or kinky hair, look for a thick styling cream that contains not only silicone but also rich moisturizers like honey and wheat protein; apply liberally and distribute with your fingers or a wide-toothed comb. (Try Hair Rules Kinky Curling Cream.) If you want to let your hair air-dry, just keep your hands off for the rest of the day (touching it can induce frizz). If you blow-dry, wait until your hair is just damp, then, aiming the nozzle of the dryer downward, dry in two-inch sections with a large round brush.