The chemistry that transforms hair from a mousy brown to a deep chocolate brunette, or from a graying blond to a golden honey, may seem like magic. In truth, it’s a torture test that leaves hair dry, dull, and rough  the very qualities that, ironically, make haircolor look drab. But if you’re one of the 70-plus percent of American women who cover their grays or brighten their natural hue, don’t worry: This is one test you can pass with flying (hair)color. Some easy changes in your hair-care habits, along with pro-recommended products, will renew your tresses’ shine and vibrancy and restore your faith in your favorite box of color’s ability to work magic.