You Use Too Much Shampoo
You've probably already heard that unless your hair is very greasy, daily washing can strip away the natural oils that leave hair looking glossy. But even if you've already cut back on your shampoo schedule, you could still be oversudsing. The detergents in shampoo do an excellent job of removing the oils that build up at your roots, but they could dry out the rest of your hair. Use just enough shampoo to work up a decent lather (no more than a quarter-size dollop) and work it only into your scalp, never your ends.
Your Conditioner Has the Consistency of Skim Milk
If you pour your conditioner out of a bottle, it's probably not rich enough to do more than detangle your hair. "For serious hair-smoothing, look for a deep conditioner that's packaged in a tub or tube," says New York City hairstylist Nathaniel Hawkins. (Our current favorite: Living Proof Restore Mask Treatment, $42 for 8 ounces; LivingProof.com
You Take Two-Minute Showers
If you really want a conditioner to improve your hair, you need to leave it on for at least five minutes, says Hawkins. Shampoo your hair as soon as you step into the shower, then comb through the conditioner (to make sure every strand is covered) and leave it on while you wash your face and body, shave your legs, sing a few rounds of "Thunder Road."
You Never Air-Dry
Heat-styling ruffles the cuticle, or outer layer, of the hair shaft; without a glossy coating, the strands can't reflect light and look dull and rough. Summer is the perfect time to pack up the blow-dryer. Blot hair with a towel to absorb excess water then use either a styling cream (if your hair is wavy or curly and relatively thick) or a moisturizing mousse (if your hair is straight and relatively fine). When you feel you must blow-dry, hold the dryer as far as possible from your hair and keep it moving. And use your flatiron sparingly: "It's for finishing a style after blow-drying, not for taking hair from frizzy to straight," says New York City hairstylist Lisa Chiccine.
You're Using the Wrong Styling Products
When your hair looks dry and lackluster, gels and sprays can compound the problem by leaving a film behind. Silky serums and rich creams are a better choice for smoothing and adding shine. And don't be chintzy, says Hawkins: Use a quarter-size dollop for chin-length hair, and at least twice that for hair that's shoulder-length or longer.
You're Too Cozy with Your Colorist...
If you're dying your hair more than every eight weeks, you're weakening each strand, making it more susceptible to breakage. To extend your time between appointments, don't veer more than two or three shades from your natural color and never put permanent dye or bleach on previously colored hair.
...But You Rarely Get a Cut
It takes only about six weeks for the ends of your hair to start to fray. If you want your style to look healthy and fresh, don't go more than two months between trims.
You Jump in the Pool with Dry Hair
Dry hair will soak up a lot of the chlorine that can leave your hair parched and your color brassy. If your hair is already wet (with tap water), it's less likely to absorb the hair-dulling chemical. For extra protection, after a quick pre-swim rinse, comb a little conditioner through and secure your hair in a low bun before you dive in. And post-swim, rinse your hair out as quickly as possible, says Chiccine.
You Don't Own a Hat
The sun breaks down the keratin fibers in the hair, making it look dull and brittle. And if you dye your hair, the UV rays will turn blonde highlights brassy and give an orange tinge to brunet shades. A wide-brimmed straw hat will protect your hair. And your skin. And look exceedingly chic.
Next: The best products for frizzy and frazzled hair