Apply a shot glass of sunscreen for every two hours of sun exposure. Most of us don't apply enough, said Dr. Spencer Holmes, a dermatologist at Park Nicollet in St. Louis Park. At best, sunscreens are water- and sweat-resistant, so reapply after two hours in the sun.

Use a sunscreen within three years. The ingredients are designed to be stable for three years, according to Manufacturers are not required to put an expiration date on labels even after the new regulations go into effect, but some include a "use by" date voluntarily.

Avoid sunscreens with the ingredient oxybenzone, which can disrupt the body's hormones and can cause allergic reactions, especially in children, according to

Spray cautiously. The FDA is exploring risks from inhaling spray sunscreen. Consumer Reports doesn't recommend using sprays on kids. Spray on the hands and then apply to the face.

Use a sunscreen with an SPF of 30 to 50. The extra protection from any sunscreen with an SPF over 50 is negligible, said Hansen. An SPF 30 blocks 97 percent of UV rays, SPF 40 to 50 blocks out 97 to 98 percent and SPF 50+ blocks up to 99 percent.