The thing about a "routine" is, you've gotta do it the same way every time. But maybe every now and then, you decide it's more important to watch the past three episodes of Downton Abbey than go through the rigamarole of removing your makeup, washing your face, toning, serum-ing and moisturizing. You might not notice it tomorrow morning, but skipping even one night of basic cleansing clogs pores because it gets in the way of cell turnover. No cell turnover = dull skin, blackheads and wrinkles.

And, if you're not consistent with the rest of your post-washing skin care regimen, whatever it involves -- applying a prescription retinol, patting a rich nighttime moisturizer around your face, using an eye cream -- you'll never see the results they promise or get your money's worth out of those products.

The fix: According to Dr. Peredo, at a bare minimum, your daily and weekly cleansing routine should look like this, no excuses: cleanse twice a day, exfoliate twice a week and wear moisturizer with sunscreen during the day, year-round. If you have acne-prone skin, skip grainy physical exfoliants in favor of chemical exfoliants like salicylic acid. To treat uneven skin tone or aging skin issues, exfoliate with a glycolic acid.

Your routine should also include regular facials -- ideally every four to six weeks. Because your skin cells turn over approximately once a month, periodic facials can remove the dead cells and reveal the healthy layer of skin underneath, says Dickman. If a regular professional facial isn't in your budget, getting one even twice per year can help. Think of it as one of your regular health checkups, like getting a pap smear or teeth cleaning (only much more pleasant).

And don't expect immediate, miraculous results -- Dr. Bellman says it takes about a month to see changes in your skin after sticking to a good routine.

You either love it (too much) or hate it. Whether you're slathering your face in thick, rich creams post-wash, or reveling in the tight, clean feeling of cleansed skin sans moisturizer, both can damage your skin.

Because oily skin is notorious for causing pimples and blackheads, people tend to dry it out with acne medications and forego moisturizer, says Dr. Peredo. But shying away from moisturizer because you think it will make your skin oilier is ... wrong. Dry skin will overproduce sebum (pore-clogging oil) to compensate for the loss of moisture.

And those of you with dry skin might be tempted to slather on moisturizer; if some is good, more is better, right? But your skin can only absorb so much product. If you overdo it, the excess moisturizer can can your pores.

The fix: "Moisturizing regularly when you have oily skin helps to control the overproduction of sebum," Dr. Peredo says. If you have oily skin, use a toner to restore your skin's pH balance and zap dead skin cells, then apply a lightweight moisturizer all over your face. Use it sparingly on the oiliest parts of your face.

And if your dry skin feels too parched, Dr. Peredo recommends switching to a heavier, more emollient moisturizer at night rather than loading up on your regular moisturizer. If you find that heavier night creams cause your skin to break out, layer a gentle moisturizer (without SPF) over a face oil for extra moisture that won't clog your pores.