The 4 most common skin-care mistakes that facialists see clients make all. the. time.

I may have a consistent skin-care regimen now, but it’s taken years of trial, error, and hundreds of beauty products to get to this place. And lest we not forget: I’ve interviewed dozens upon dozens of the top estheticians in the world to get intel on what to do to my skin, and more importantly what not to do.

Here’s the brief: Retinol is a must-have ingredient for pretty much everyone’s skin-care routine, add an acid toner to your routine (like, now), and applying hyaluronic acid to damp skin can make it work even better for you. As for the stuff to stop, well that will take a little more airing out. Here, I’ve rounded four pieces of advice to get your skin glowing.

1. Skin misdiagnosis

People all think they know whether their skin is dry, oily, acne-prone, or—the most popular—sensitive. But if you’re not sure, you can be using an entirely wrong regimen. “The biggest issue I see is misdiagnosis—people think their skin is oily but their pores are just clogged, or they think their skin is sensitive but it’s actually dry and acting up because the skin barrier has been stripped,” says Angelina Umansky, facialist and founder of Spa Radiance. “By not analyzing your skin correctly, you end up treating it with the wrong products. When you’re sick, you go to a doctor for a diagnosis, so it’s best to leave your skin analysis to the estheticians and dermatologists.”

2. Stripping the skin when cleansing

As we recently reported, close to 40 percent of people think their skin’s clean when it feels tight, which actually just means you’ve just stripped your skin. “Another common issue I see is people stripping their skin when they wash it,” says Umansky. “Foaming cleansers, facial brushes, and aggressive toners can weaken your skin barrier.” Obviously these products still exist because they’re great options for some skin types, but again, you want to make sure that yours is a good match.

Another thing to check on? That your acid toner is formulated with hydrating ingredients to balance out the exfoliation. (She loves the P50 by Biologique Recherche.) “Check the ingredients list, and if the acid is high on the list and you also see things like alcohol or astringents, or witch hazel, it can strip your skin’s protective barrier,” says Umansky. Leave facial brushes for once a week with a gentle, milky cleanser.

3. Over-exfoliating

We’re in the heyday of exfoliants—it seems every latest skin-care product is spiked with some sort of exfoliating acid. Which is great. But all good things can be overdone. “These days, everyone seems to be into exfoliation,” says Sarah Akram, a Washington, D.C.-based facialist. “The problem is that your skin doesn’t need to be exfoliated everyday. Every time you exfoliate, you strip top layers of skin from your face by chemically or physically breaking apart your skin cells.” Because of this, she points out that if you don’t give your skin enough healing time, it can become sensitized, more prone to sun damage and UV radiation, and become discolored and inflamed. “I suggest limiting exfoliation to one-to-three times a week,” says Akram.

4. Skipping SPF

Obviously, you’re already a pro at slathering on your sunscreen on the reg. But Akram stresses the fact that it’s so incredibly important, even when the sun’s not shining. “UVA and UVB rays are responsible for the breakdown of collagen and elastin, skin discoloration, and irreparable DNA damage that causes harmful skin cancers,” she says. If there’s anything every skin pro we talk to will tell us, it’s this: SPF 365 is the number one thing you can do for your skin.

For more pointers, here are some more esthetician skin-care tips to follow, stat. And this is the first sign that you’re over-exfoliating your skin.