Anyone who knows me knows I'm obsessed with sun protection—but there's a good reason for it: sun exposure is the number-one cause of premature skin aging. Plus, it's a lot easier to protect from the sun than it is to treat damage once it's already occured. 

Since summer is almost here, I thought I'd share a few of the tips and tricks I share with my clients. Read on for my favorite sunscreens, how to use them, and what to do if you're already dealing with sun damage. 

—First things first: Always Wear SPF—
I've said it before and I'll say it forever—sunscreen is a non-negotiable part of your A.M. skincare routine. There are no exceptions to this rule, even if you're planning to stay indoors all day (UV rays can pass through windows). Consider it an insurance policy against future fine lines, wrinkles, hyperpigmentation, and other signs of sun damage.

It's a lot easier to remember to wear SPF when you have a formula you love. My favorite is Supergoop Play Everyday Lotion SPF 50 ($22) because it's so easy to apply. It absorbs quickly with no whitecast or sunscreen smell. For those with acne-prone skin, I recommend Control Corrective Oil-Free Sunscreen SPF 30 ($38) because its lightweight and non-greasy. Both options look great under makeup! 

—Use Makeup with SPF, Too—
If you're going out and putting on some kind of foundation, I always recommend using one with SPF in addition to your sunscreen. That way, you can touch up your sun protection along with your makeup throughout the day—it's important to repply often so you're fully shielded. Supergoop CC Screen 100% Mineral SPF 50 ($39) is my pick for lightweight coverage, color correction, and sun protection in one. 

—Don't Forget Your Lips—
You may not think to put SPF on your lips—especially if you're not at the beach or pool—but they're just as prone to damage as the rest of the face. Supergoop Shine On Lip Screen SPF 40 ($22) can be layered over any lip color, adding UV protection and a sheer, glossy finish. I always have several of these on hand, so I'm never without it!

—Apply a Vitamin C Serum in the A.M.—
For an extra layer of defense against free radical damage, apply a vitamin C serum before your sunscreen. Vitamin C is packed with antioxidants that protect skin from free radical damage—a side effect of UV radiation—and it can also help repair some of the visual effects of sun damage, such as dark spots. iS Clinical Super Serum Advance+ ($155) is a powerful Vitamin C serum that works for most skin types. Have sensitive or acne-prone skin? Try iS Clinical Pro Heal Serum Advance+ ($155) instead.

—Treat Sun Damage Early—
If you already have signs of sun damage, start treating them right away before they progress. I always suggest starting with Retinol Reform ($88) the gold standard for retinol serums. It's award-winning formula is clinically proven to minimize fine lines, wrinkles and brighten skin in just 12 weeks.* You can also use Dr. Dennis Gross Alpha Beta Peel Pads ($88) for extra skin-brightening power. Add them to your routine once or twice a week, on nights that you aren't using retinol—they'll help amplify your retinol glow.