1. Hair color. Anytime you dye your hair, you’re increasing the diameter of each strand, which can help add volume when your hair is sparse and fine. As a general rule, ask your colorist to make sure highlights are finer at the top of the head, where hair is the thinnest, and more intense at the bottom, where it’s thickest, says Eva Scrivo, a hairstylist and the owner of the Eva Scrivo Salon in New York City. And beware: A color that contrasts with your scalp (blonde tones if your scalp is dark, deep brunettes if your scalp is light) will make any visible scalp more obvious.