"Salty food, alcohol, and lack of sleep are the main culprits of puffy eyes in your 20s," says Great Neck, N.Y., dermatologist Jeannette Graf. Drinking more water (while cutting down on the burgers and booze) goes a long way toward solving the problem, as does a daily swipe of a cooling eye stick. Look for one with vitamins E and C, which constrict blood vessels and prevent fluid from pooling. Need immediate relief? It's a cliché, but it works: Chilled cucumber slices (or cuke-infused eye pads) reduce swelling, instantly tightening the skin.