The best way to keep your skin from getting wrinkled, saggy, and speckled is sunscreen, SPF 30 at the minimum. Broad-spectrum formulas (meaning they shield against both UVA and UVB rays) with Mexoryl or Helioplex offer the longest-lasting protection. Apply a whole tablespoon to your face, and the equivalent of a shot glass on your body. For workdays, reapply before your commute home if the sun is still out—even if you'll be in a car. And for days when you'll be outside for an extended period of time, reapply every two hours. We know it's a pain, but come on—you'll get the last laugh instead of the first laugh lines.

Now, we're not taking away all your fun—you can still have a glass of something. But drink more than one cocktail a day, and your skin suffers. Alcohol increases the level inflammatory agents in the bloodstream—"which can hasten skin sagging over time," says Fredric Brandt, a dermatologist in New York City and Coral Gables, Florida.

Skin care doesn't stop at your jawline. "These areas are almost always exposed, and yet they rarely receive same level of hydration and sun protection as the face. But the skin there is more delicate and just as vulnerable to photoaging," says Los Angeles dermatologist Howard Fein. The fix is simple: The next time you apply serum, face cream, or sunscreen or give yourself an exfoliating treatment, extend everything down to your décolletage.

Why bother, you think. Here's why: Skip washing your brushes and you could wind up with muddied colours, clogged pores, and bacterial infections. Once every three weeks, lather brushes with a gentle shampoo, rinse well, and let them dry overnight or use wipes. Another option:Clinique The Brush Collection - they're treated with a microbial solution that destroys germs. (You still have to wash them, but only about once a month.)

Resting your chin or cheek against a phone can lead to breakouts, whether or not the phone is clean and bacteria-free. "Just leaning your face against it can cause friction, occlusion, and heat, all of which can make you break out," says Bay Area dermatologist Katie Rodan. If your chatting habit is too ingrained to shake, consider a headset.

Sorry—while squeaky-clean pores may initially feel good, "harsh cleansing or too much exfoliating can actually exacerbate oil production and worsen breakouts by spreading bacteria," Fein says. A gentle alternative: Use a glycolic peel three times a week.

"Sleep deprivation causes stress, which can aggravate all skin conditions, including acne, eczema, and psoriasis," says Karyn Grossman, a dermatologist in Santa Monica and New York City. "Sleep is also the time when your body repairs the damage from the day, and interrupting that process will slow down cell turnover." In the short term, this can mess with the way blood flows to the skin, which can make your complexion sallow.

We know, we know: It's tempting. But the reality is that squeezing a pimple just pushes bacteria deeper into the pores, causing inflammation, infection, and scarring—and almost doubling the zit's life span (from about one week to two). Napalming it with the harshest chemicals in the bathroom won't help, either. "Treating any breakout with too much benzoyl peroxide damages the skin around the spot and can cause more irritation," says Boston dermatologist Jeffrey Dover. Here's what you should do: Use a spot treatment with no more than 2.5 percent benzoyl peroxide at night, and reapply it to major zits in the morning.  For persistent acne, a prescription retinoid, such as Retin-A, helps prevent blocked pores—but doctors warn it can exacerbate the redness of existing pimples, so avoid slathering it over full-blown ones.

Bronzer? Fine. Self-tanner? Fine. The real thing? So not fine. "In trying to protect itself from continued exposure to the sun, skin thickens and produces melanin, the pigment that darkens cells," explains Miami dermatologist Flor Mayoral. "Any pigment change from UVA or UVB light can cause premature aging and increase the likelihood of skin cancer." And tanning beds can be even worse, since they emit concentrated UVA light, which penetrates deeper than the combination of UVA and UVB rays found in sunlight, Mayoral says. (Indeed: They've recently been considered to be on par with arsenic and mustard gas in the top cancer risk category.) Be sure to protect yourself by applying a broad-spectrum sunscreen with a minimum of SPF 30 every day, and if you're in the sun, reslather it every two hours. And never, ever use a tanning bed. Instead use tan in a can.

Along with lifting your mood, exercise increases blood flow to the skin, causing a healthy-looking flush. Both immediately and over time, it has been shown to decrease tension, which can result in better skin. "When you're stressed, cortisol levels rise, and that leads to acne and other skin aggravations," says Rodan. "Lessen your cortisol spikes, and your skin will become smoother and clearer." (Of course, you should wash your face immediately after that workout.)

"I ask patients to walk me through their routine, and they bring in shopping bags full of products," says New York City dermatologist Patricia Wexler. "They add things without checking to see whether they're duplicating ingredients or realizing that some aren't compatible." Sometimes, active ingredients cancel one another out—Other times, they double up and cause irritation or skin damage. "Negative interactions are most likely to happen if someone is treating different problems at the same time, such as sun-damaged skin and adult acne, and the ingredients are either too harsh together or incompatible," says Baumann. The biggest culprits: retinol, glycolic acid (aka AHA's), vitamin C, and benzoyl peroxide—avoid layering them, or at least try to use them at different times of day.