Not all sunscreens are created equal, according to the American Academy of Dermatology. For maximum protection, use a broad-spectrum or multispectrum sunscreen that protects your skin from both UVA and UVB rays, the two types of ultraviolet radiation from the sun that can cause skin damage, including skin cancer.
In addition, choose a sunscreen that has a sun protection factor (SPF) of 30 or higher. SPF is a measure of how effective a sunscreen is at blocking harmful UVB rays. The higher the SPF, the more protection the sunscreen offers.
Finally, choose a sunscreen that is water-resistant. Apply generously to all exposed areas of skin, according to the directions on the bottle.