If you want beautiful skin, there are endless tricks and tips you can try. Some are simple and attainable while others … not so much. Drinking gallons of water? Doable. Smearing bird poop all over your face once a week? No thanks.

However, there are some tried and true, proven-by-science skin care rules, and the research to back them up gets more compelling every day. For example, daily sunscreen use isn't just for skin cancer prevention -- there's hard evidence it can seriously slow skin aging. And it's not just about what you put on your skin, but also what you put in your body.

"There is a consumer mindset shift to focusing on skin health as part of a holistic anti-aging skin care regimen," says Elizabeth Arden Consulting dermatologist Dendy Engelman, MD. " The same way they focus on diet and exercise as part of overall health, they are now approaching skin care."

So if you want to have the most amazing skin possible -- for as long as possible -- follow these simple guidelines. We promise they're completely bird-poop-free.

Washing your face at night goes beyond taking off your makeup. You're also removing dirt and particulate pollution from your face. And new research shows that this pollution contributes to wrinkles and brown spots -- possibly as much as sun exposure. And pollution has been linked to skin conditions like eczema and psoriasis, as well. For the healthiest skin possible, wash your face every night -- no lazy girl excuses.

Just because you're layering on a serum and moisturizer every morning and night, doesn't mean the serum and moisturizer are doing much to improve your complexion. And if the active ingredients like antioxidants and peptides are sitting on top of your skin without sinking in, you're essentially wasting the money you spent on those products. In order to maximize the benefits of your skin care, you need a healthy skin barrier (the outermost layer) -- because when your surface layer is functioning well, it allows skin-enhancing ingredients to penetrate more easily.

Using a product like Elizabeth Arden's SUPERSTART Skin Renewal Booster, $65, helps skin's ability to repair and renew while allowing your serum and moisturizer to work harder. It's packed with botanicals and probiotics for optimal skin health.

"By incorporating a product like SUPERSTART into your regimen, you are helping the skin function at its highest potential, and by doing so maximizing the results of all products you have been using," says Engelman.

You've heard it a million times, but let's make it a million and one for good measure: You need to wear sunscreen daily. Not just in the summer. Not just when you're going to the beach. And not just in your makeup (unless you're slathering on a teaspoon of the stuff). You need to wear a sunscreen with at least an SPF 30, and you should apply it every morning for the healthiest skin possible.

An Australian study of 900 men and women found that people who used sunscreen religiously for four and a half years showed no signs of skin aging. We repeat: They did not age. So stop hunting for that fountain of youth, and spend your time shopping for a sunscreen that you like instead.

Here's the problem with thin skin: It generally lacks some (or all) oil glands, which means it dries out quickly, and the barrier is easily compromised. "Pay special attention to eyes, neck and décolleté," says Engelman. "That skin is thinner and tends to be the first to show signs of aging."

And wrinkles on your chest or the backs of your hands will give away your age -- even if you've worked hard to keep your facial skin looking as young as possible. For amazing looking skin from head to toe, use your facial skin care routine anywhere that's exposed -- i.e. your neck, chest and hands -- and pay special attention to the delicate skin around your eyes.