Over exfoliating
More scrubbing does not equal healthier skin, says Dr. Engelman, and in fact, it can trigger inflammation and weaken the skin's barrier function. "If the barrier function is damaged, skin becomes vulnerable to infection from microorganisms, such as bacteria and fungus, and can become sensitive and irritated. Even if the barrier function isn't visibly damaged, the skin may experience a low amount of inflammation, which over time prematurely ages skin," says Dr. Engelman. "Start with a once or twice a week exfoliation; your skin will tell you when you're doing it wrong: it will feel red, painful, or start to sting with your regular topical regimen," says Dr. Nazarian. Most normal skin types can handle a gentle scrub, or a chemical exfoliation with glycolic acid or lactic acid, says Dr. Nazarian.

Rubbing products into your skin
Rubbing can easily irritate your skin. Always use light, gentle upward strokes when applying products to the face and neck, says Sejal Shah, M.D., a dermatologic surgeon in New York City. Try a lightweight serum like Olay Regenerist Miracle Boost Concentrate, which not only easily absorbs into the skin to enhance hydration, but it smoothes the texture as well.

Cleansing with hot water
Hot water can strip the natural oils from your skin, says Dr. Engelman, leaving it dry and vulnerable to cracking. Losing these oils compromises the skin's barrier, making it susceptible to irritants. Hot water also causes dilation of blood vessels — which is linked to inflammation. It's best to shower and wash your face in warm-to-lukewarm water instead.

Not changing your pillowcase
Your pillowcase can be quite the haven for bacteria and germs: Each night it accumulates more oils from your hair, saliva and bacteria from you skin, says Dr. Nazarian. As you toss and turn in your sleep, that mixture moves from the pillowcase to your face and back again. Change your pillowcase at least weekly to keep skin at its best.

Going to bed without cleansing
Skin renews itself best at night, and leaving it exposed to free-radical particles in the skin that may accumulate throughout the day only perpetuates skin aging and damage, says Dr. Nazarian. Not to mention, sleeping in your makeup can increase your acne risk and rosacea flares, since bacteria trapped under makeup increases the risk of inflammatory skin conditions.

Storing Your Products Improperly

We’re not about to suggest that you need a separate mini fridge for all of your skincare products. (Though this is a thing!) But we’re also not going to suggest keeping your products anywhere too warm or too moist (the latter particularly applies to things like razors, trimmers, scissors, combs, tweezers, etc). Most products are fine at the range of natural cool and warm temperatures throughout the year, but if they receive direct sunlight on a hot day, they can heat up and deactivate in a jiffy. It’s harder to mind temperature control when you travel, but pay particular attention to active ingredients like Vitamin C, prescription retinol, antioxidants, and UV filters. These finicky ingredients are also top of mind for the next tip, too…

Not Layering Hyaluronic Acid

Hyaluronic acid deserves all the praises it receives as a mega moisturizer. It can hold up to 1000x its own weight in water by extracting moisture from the air. (On its own, it is also extremely moisturizing, too.) However, if you apply hyaluronic acid in winter, remember one thing: Always follow it with a moisturizer, to trap the ingredient inside the skin’s barrier. If you don’t—and if you’re in a dry, cold environment—hyaluronic acid goes digging for moisture from deep within the skin instead of at the surface. This depletes moisture levels even further, and leads to even drier skin than you started with. It’s good practice to always apply a moisturizer over your serums, but especially in dry environments when the lack of humidity takes a toll.

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