Greasing your hair to increase volume sounds about as logical as a cheeseburger diet. But guess what, it works. "Light plant and flower oils"—such as palm or coconut—"help dissolve the heavier oils on your scalp," Philip B. explains. "When you shampoo, you'll get a much deeper clean."
Leonor Greyl Huile de Palme oil treatment, $49; folica.com.