What is the best approach to sunscreen?

Shot glass of sunscreenUse a sunscreen with a broad-spectrum protection of SPF 30 or greater which blocks both harmful UVA and UVB rays. Re-apply every two hours and after exposure to water through swimming or sweating. It requires approximately one ounce (one shot glass full) of sunscreen with each application to cover all exposed skin. Always check to be certain that sunscreen has not expired.