Cotton is cool, but performance blends are cooler. Look for moisture-wicking fabrics like Tencel, bamboo, or linen-cotton hybrids that let your skin breathe and your pits stay unbothered.

Who doesn’t want to look like an effortlessly cool French guy taking in a little tennis at Stade Roland Garros? No one, that’s who. Which is why it’s so nice—with the French Open beginning ...