When it comes to skin care, most of us fall into one of two camps. There are those of us who never change our routine, using the same ill-suited face wash and moisturizer from our high school days. Then there's the other group, who embrace treatments like Botox and acid peels before there's a wrinkle in sight.

As we age, our skin changes. What worked in our 20s won't do us any favors in our 30s — or 40s. If the goal is to maintain a youthful, dewy glow well into our golden years, and look just as radiant every decade in between, we need to tailor our skin care regimen to the number of candles on our birthday cake. We got the lowdown from the country's top skin care experts on the products we should be using in our 20s, 30s, 40s, and beyond. Here, how to put your best face forward at every age.

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At this age, your goal is to preserve and protect. In your 20s, many of the skin issues you see come from carefree living (and neglect): partying on weekends, drinking too much, pulling all-nighters and basking in the sun without sunscreen. There might be lingering acne from the teen years as well. Hard living comes at a cost, though: fine lines can start to creep up in the second half of your 20s. To stave them off and counteract your skin sins, it's important to start a consistent skin care routine that involves SPF.

Your ideal regimen:
Step 1: Use a gentle foaming cleanser that will remove makeup and excess oil, but won't dry out your skin.
Step 2: For day, use a light moisturizer that contains sunscreen with UVA and UVB protection (the experts say this is something you cannot skip -- EVER. Look for a product that contains either zinc oxide, titanium dioxide, avobenzone or Mexoryl. New York based dermatologist Dr. Heidi Waldorf recommends EltaMD UV Clear, $30. "It is an ultra light, quick absorbing, oil free moisturizer with SPF 46 and zinc oxide, that feels light but provides hydration, so it's an ideal daily moisturizer for face and neck." She also recommends La Roche-Posay Anthelios 50 Mineral Ultra Light Sunscreen Fluid, $33.50, with SPF and titanium dioxide for patients with very oily skin.
Step 3: If you get mild breakouts (not serious acne -- your dermatologist should recommend the ideal treatment for that), use a spot treatment containing salicylic acid or benzoyl peroxide. And whatever you do, don't pick -- it can lead to long-lasting scars.
Step 4: If you are one to stay up all hours of the night drinking and smoking, use an antioxidant to counteract the damage from your partying ways. Apply a serum at night that contains pomegranate extract (ellagic acid), vitamin C or grape seed extract. Antioxidants,"eliminate damaging free radicals responsible for most of what we perceive as skin aging, including fine lines, pigment changes and textural irregularity," says Dr. Howard Murad, founder of Murad Skincare.
Step 5: At night, cleanse and spot treat any breakouts (again with a treatment containing salicylic acid or benzoyl peroxide), and follow with a basic light moisturizer.
Step 6: It is okay to introduce eye creams and other anti-aging products as long as they are not too harsh. If it doesn't make your skin look better or if the product is irritating, skip it. Instead, Murad recommends looking for hydrating ingredients like ceramides, sodium PCA, amino acids, essential fatty acids, and alpha and beta hydroxy acids. "They protect against dryness and fine lines by replenishing naturally occurring skin lipids."

Discoloration caused by sun damage or melasma (aka the mask of pregnancy that can also be caused by birth control), and fine lines are likely two of your biggest skin challenges. "At this point, you need to start exfoliating regularly because skin only exfoliates naturally every 35 days as opposed to every 14 in your 20s," says Olga Lorencin, aesthetician and co-owner of Kinara Spa in Los Angeles.

Your ideal regimen:
Step 1: Women in their 30s need a cleanser that does a little more than the ones you used in your 20s. Dr. Waldorf recommends a formula that "removes makeup and lightly exfoliates using PHAs (gluconolactone and maltobionic acid), and reduces inflammations with a botanical complex including chamomile and aloe. NeoStrata Skin Active Exfoliating Wash, $35, accomplishes both.
Step 2: "Use an eye cream both day and night to hydrate the skin around the eyes and increase suppleness," says Murad. This will help diminish any lines that may be appearing. An eye cream with a broad based SPF works well in the day, and a hydrating eye cream is ideal for the evening.
Step 3: For day, before applying sunscreen, use an antioxidant-rich moisturizer, serum or lotion. "There is some evidence that antioxidants act synergistically with sunblock to help guard against photo damage," says Waldorf. Even better, she says, they may also be able to undo some of the damage that's already been done. If you were using a quality product in your 20s, keep on using it, but if you need an upgrade, Caudalie Vinexpert Firming Serum, $88, contains a potent form of reservatatrol from grape vines (the "magic ingredient" that keeps popping up in current studies), plus peptides and hyaluronic acid to boost moisture.
Step 4: Add a retinoid to your regimen to help improve the overall texture and tone of your skin. The highest-strength retinoids are prescription only, but over-the-counter retinol is a close second. Everyone's skin is different, so the strength you need will vary on an individual basis. Apply retinoids at night (sunlight deactivates retinol, making it worthless), and avoid putting them on your upper eyelids -- retinoids can be too irritating on your delicate eye area.
Step 5: If your skin feels like it needs additional moisture after applying a retinoid, use a basic hydrating cream that doesn't contain additional retinol. Other acids, such as alpha hydroxyl acids, may improve the hydrating effects of a product, but "you want to avoid over treating your skin," says Waldorf.

In your 40s, expression lines between your brows and around your eyes and mouth don't disappear like they did in your 30s. "Your estrogen level is tapering so your skin will become dryer," says Lorencin. The neck and décolleté area might start to look crepey as well. Overall you'll need to add moisture and collagen-building ingredients like peptides.

Your ideal regimen:
Step 1: Cleanse using a basic non-foaming, non-drying cleanser in combination with a gentle face cleansing brush to help remove dead skin cells. Because you'll use retinol (a chemical exfoliant) regularly, you'll need to get rid of any flaking skin.
Step 2: Use SPF daily to prevent further damage and choose a product that contains antioxidants to fight free radicals and help reverse some of the damage you already have.
Step 3: Retinoids and peptides are two ingredient groups that you should add into your routine if you haven't already. Peptides can help rebuild collagen, especially when used in combination with skin texture-improving retinoids like retinol. To get both ingredients in one dose (and at one price), opt for a serum like Rodan + Fields Anti-Age Night Renewing Serum, $89.
Step 4: Dr. Murad suggests using an anti-aging product specifically formulated for the neck that includes phytoestrogens, retinols and licorice root to help smooth, plump and erase discoloration, such as Dr. Murad's Rejuvenating Lift for Neck and Decollete, $55.
Step 5: Use a moisturizer that has a high level of glycerin or hyaluronic acid to help skin retain the moisture it needs.

"Moisture, moisture, moisture," says Waldorf. This should be your main concern in your 50s. Loss of tone, hollow eyes and sagging are your biggest issues, and creams and serums can only do so much. If you're looking for more dramatic results, in addition to using powerful products that contain peptides, retinoids, or alpha hydroxy or amino acids, consider talking to your derm about laser treatments and other non-invasive or invasive skin rejuvenation options.

Your ideal regimen:
Step 1: Use a cream cleanser that will hydrate skin while it cleanses.
Step 2: Choose a moisturizing cream that contains SPF to keep skin hydrated and protected. Because ingredients like retinoids can make skin more sensitive to the sun, daily use of sunscreen is a must.
Step 3: For day, apply a peptide-rich serum under your SPF daily to help build collagen. Look for one that also contains antioxidants to fight free radicals or hyaluronic acid to lock in moisture. PCA Skin pHaze 25 ExLinea Peptide Smoothing Serum, $102, contains all three ingredients.
Step 4: At night, apply a retinoid before your moisturizer. Your moisturizer should contain phytoestrogens to help with hormonal aging, such as Ilike Phytoestrogen Moisturizer, $68.
Step 5: Though it sounds too simple (and inexpensive) to be true, a simple petroleum jelly is a great way to lock in the moisture from your moisturizer, which is more important now than ever. One thing to note, petroleum jelly prevents water loss but doesn't attract moisture, so you can't actually skip moisturizer altogether.