SAN FRANCISCO — After enduring an especially brutal winter, Americans may be tempted to catch more than a little sunshine this summer.

But the impulse is often clouded by two conflicting public-health issues. How do you strike a balance between protecting your skin from the sun’s harmful ultraviolet rays without robbing yourself of the health benefits of vitamin D, which the sun aids the body in producing?

Since vitamin D is available in food sources as well, a general rule to remember, dermatologists say, boils down to this: Wear sunscreen. Reapply it every few hours when you’re in the sun. And seek shade during peak sun hours.

“The sun has an effect on happiness and pleasure,” acknowledges Dr. David Leffell, professor of dermatology and surgery at Yale School of Medicine in New Haven, Conn.

But it has a dark side, he says. “We need to understand it and approach our sun-seeking behavior in moderation.”

It’s easier to practice good “sun hygiene” than you might think. Here are a few tips, including highlights of new sunscreen ratings by Consumer Reports.

n Think of sunscreen — whether you choose a lotion, spray or cream — as part of an overall strategy to avoid increasing your risk of premature wrinkles and skin cancer. The strategy also includes wearing wide-brimmed hats and tight-knit clothing and saying no to baking yourself in the sun or a tanning salon.

• Choose sunscreen with a sun protection factor of no less than 30 and apply it before going out in the sun. It’s more effective that way and keeps it from staining your clothes at the same time, says Jamie Hirsh, senior associate editor for Consumer Reports Health in Yonkers, N.Y.

Make sure you use enough of it. Apply two to three tablespoons to cover all exposed skin. That’s about equivalent to filling a shot glass. And put sunscreen on easily forgotten areas prone to sunburn such as your neck and the tops of your ears and feet, if you’re wearing sandals.

• Reapply sunscreen every few hours. “Don’t just put it on once and think you’re good to go for the day,” says Hirsh. “That’s even true for the water-resistant ones. When you towel off (after swimming,) you’re mechanically removing sunscreen.”

Dr. James Spencer, a member of the board of directors for the American Academy of Dermatology and a dermatologist in St. Petersburg, Fla., says this is where many well-intentioned people can fall down on the job. “The hard part is you have to reapply it every three or four hours. It’s inconvenient.”

• Choose brands that perform well in real-world tests of whether they meet their claims of water resistance and filtering out both kinds of radiation — the deeper-penetrating UVA type, responsible for tanning and aging the skin, and the UVB type, which causes sunburn.

For its July 2011 edition, Consumer Reports tested 22 sunscreen brands. The magazine recommends nine of them for staying on in water and being “excellent” at protecting skin from UVB radiation and “very good” at protecting from UVA radiation: Banana Boat Sport Performance SPF 30 and Banana Boat Sport Performance SPF 100, Coppertone Sport Ultra Sweatproof SPF 30, CVS Fast Cover Sport SPF 30, Walgreens Sport SPF 50 and Ocean Potion Kids Instant Dry Mist SPF 50. Three on the recommended list were also rated “best buys:” Up & Up Sport SPF 30, No-Ad with Aloe and Vitamin E SPF 45 and Equate Baby SPF 50.

• Don’t let price be a deterrent to using sunscreen. About half of products recommended by Consumer Reports are store brands, not name brands, Hirsh says. One of its “best buys,” the No-Ad product, sells for as little as 59 cents an ounce.