Tight black leggings—in the manner of little black dresses—come in all shapes and sizes. "The goal is to highlight the thinnest point of your leg," says Cher Coulter. That's usually below the knee and above the fullest section of the calf, but if you're tall, an above-the-knee crop will balance your proportions. If your thighs and calves are equally wide, try a bootcut version that nips in at the knee and flares a bit at the ankle. Black slims the back view too.
Nylon-Lycra pants, Lululemon Athletica, $98; lululemon.com.Read MoreLess