Choosing a sunscreen isn't as simple as it used to be.The next generation of sunscreens is just hitting the market -- including L'Oreal's Anthelios SX and products containing Helioplex -- designed to offer fuller protection against both UVA and UVB rays. Given all the new options, how do you know which is the best sunscreen for you?Finding the Best SunscreenSunscreens help shield you from the sun's dangerous ultraviolet (UV) rays in two ways. Some work by scattering the light, reflecting it away from your body. Others absorb the UV rays before they reach your skin.A few years ago, choosing a good sunscreen meant you just looked for a high sun protection factor (SPF) -- which rates how well the sunscreen protects against one type of cancer-causing UV ray, ultraviolet B (UVB.) "SPF refers to blockage of UVB rays only," says Leffell.Research soon showed that ultraviolet A rays (UVA) also increase skin cancer risk. While UVA rays don't cause sunburn, they penetrate deeply into skin and cause wrinkles. The Environmental Protection Agency estimates that up to 90% of skin changes associated with aging are really caused by a lifetime's exposure to UVA rays.The New Broad-Spectrum SunscreensSo which is the best sunscreen for you? Clearly, you'll want a sunscreen with broad-spectrum or multi-spectrum protection for both UVB and UVA. Ingredients with broad-spectrum protection include benzophenones (oxybenzone), cinnamates (octylmethyl cinnamate and cinoxate), sulisobenzone, salicylates,titanium dioxide, zinc oxide, avobenzone (Parsol 1789) and ecamsule (Mexoryl SX).SPF 15 or higher for UVB protection. The SPF factor rates how effective the sunscreen is in preventing sunburn caused by UVB rays. If you'd normally burn in 10 minutes, SPF 15 multiplies that by a factor of 15, meaning you could go 150 minutes before burning.For the vast majority of people, SPF 15 is fine. But people who have very fair skin, a family history of skin cancer, or conditions like lupus that increase sensitivity to sunlight should consider SPF 30 or higher.Keep in mind that the higher the SPF, the smaller the increased benefit: contrary to what you might think, SPF 30 isn't twice as strong as SPF 15. While SPF 15 filters out 93% of UVB, SPF 30 filters out 97%, only a slight improvement.UVA protection. There is no rating to tell you how good a sunscreen is at blocking UVA rays. So when it comes to UVA protection, you need to pay attention to the ingredients.Look for a sunscreen that contains at least one of the following.: ecamsule, avobenzone, oxybenzone, titanium dioxide, sulisobenzone, or zinc oxide. Any of those should do the trick.Ecamsule. One newly approved ingredient that blocks UVA is ecamsule. It's been available in Europe and Canada, as Mexoryl SX, since 1993. In the U.S., ecamsule is now sold in L'Oreal's Anthelios SX products. It isn't cheap. A 3.4 ounce tube -- barely enough for 4 full-body applications -- can run $30.Avobenzone. Neutrogena's Helioplex isn't really a new ingredient; it's a "stabilized" version of a common UVA-blocker called avobenzone (or Parsol 1789). Unless it's stabilized, avobenzone breaks down when exposed to sunlight -- exactly what you don't want in a sunscreen. You'll find stabilized avobenzone in other sunscreens, too, like Active Photo Barrier Complex and Dermaplex. For instance, any brand-name sunscreen that has avobenzone is stabilized. If you want to spend $30 on a bottle of sunscreen, go ahead. But you can get equally good protection for a lot less.Titanium dioxide or zinc oxide. Less expensive options for UVA protection have been available for a long time. Old sunscreens with titanium dioxide or zinc oxide used to make people look pale and ghostly. But newer manufacturing techniques have resolved the problem.Water and sweat resistance. If you're going to be exercising or in the water, it's worth getting a sunscreen resistant to water and sweat.But understand what this really means. The FDA defines water resistant sunscreen as meaning that the SPF level stays effective after 40 minutes in the water. Very water resistant means it holds after 80 minutes of swimming. These sunscreens are in no way water-proof, so you'll need to reapply them regularly if you're taking a dip.A brand you like. Personal preference is really important.Kid-friendly sunscreen. The sensitive skin of babies and children is easily irritated by chemicals in adult sunscreens, so avoid sunscreens with para-aminobenzoic acid (PABA) and benzephenones like dioxybenzone, oxybenzone, or sulisobenzone. Children's sunscreens use ingredients less likely to irritate the skin, like titanium dioxide and zinc oxide. Unlike chemical ingredients, these protect babies' skin without being absorbed.For kids 6 months or older, look for a sunscreen designed for children with an SPF of 15 or higher. The American Academy of Pediatrics recommends that babies under 6 months be kept out of the sun altogether.Sunscreen for skin problems or allergies. People who have sensitive skin or skin conditions likerosacea may also benefit from using sunscreens designed for children. Go for titanium dioxide or zinc oxide instead of chemicals like para-aminobenzoic acid (PABA), dioxybenzone, oxybenzone, or sulisobenzone. If you have skin irritation or allergies, avoid sunscreens with alcohol, fragrances, or preservatives.Other sunscreens include moisturizers or other ingredients for people with dry or oily skin. As long as they meet the UVA and UVB requirements above, you can give them a try and see what works best.How to Wear SunscreenWhile choosing the right sunscreen is important, it won't help much if you don't use it daily and correctly. Use these tips from the experts.Apply the sunscreen 15 to 30 minutes before you go out in the sun. For woman, sunscreen can be applied under makeup. Use about 1 ounce (or 2 tablespoons) to cover your whole body. Don't skimp. A number of studies show that people simply don't use enough -- and only get 10% to 25% of the benefit.Don't forget the easy-to-miss spots, like the tips of your ears, your feet, the back of your legs, and, if you have one, your bald spot. Since your lips can also get sunburned, use a UV-protective lip balm and reapply it regularly.No matter how long-lasting it's supposed to be, reapply sunscreen at least every 2 hours, and more often if you're sweating or getting wet.Pay attention to the expiration date on the bottle. Sunscreen loses its effectiveness over time.Wear sunscreen whenever you're out during the day -- and not only when it's hot and sunny. On a grey, overcast day, up to 80% of the dangerous UV rays still make it through the clouds. And during the winter, exposure to the sun's rays still can have damaging effects on your skin.Sunscreen Isn't EnoughSome people have the impression that wearing sunscreen makes them fully protected against the sun's rays. But that's not the case. No sunscreen can do that.No matter how high the SPF, no matter how thickly you slather it on, sunscreen will never fully protect you, experts say. This misunderstanding can be dangerous: people who think they're safe wind up spending too much time in the sun and raise their risk of skin cancer and other problems.Even your clothes may not protect you. The average cotton T-shirt only has a pitiful SPF of 4.So in addition to wearing good sunscreen, you still need to take other precautions:Stay in the shade when possible.Wear sunglasses.Stay inside when UV radiation levels are highest, usually from 10 a.m. to 4 p.m. Wear a broad-brimmed hat.Wear sun-protective clothing, preferably with a UVP (ultraviolet protection rating) on the label. At least wear clothes that are dark and tightly woven, which offer a bit more protection.