1. Shaving
 “Using a razor to groom your eyebrows can be dangerous due to potential nicks,’’ says Robert Dorin, MD, a hair loss specialist. “It will also cause the hair to appear coarser when it grows back in, since you’re not fully removing the strands from the follicles.”
 Plus, it couldn’t really be more imprecise—you’re basically mowing down clumps of hair at a time—which can result in uneven hair lengths, gaps, and an irregular shape. Trade the blade for tweezers or head to a pro for waxing or threading. 
  2. Getting brows waxed at a place that “double dips.” When the same wax is used on multiple people and the stick is dipped back into the wax after it touches skin, it can transfer bacterial, viral, and fungal skin issues like staph, herpes, and warts, says New York City dermatologist Ariel Ostad, MD. The double-dipped stick carries with it loads of bacteria that will only die if the wax is heated to at least 180° (which your wax won’t be or it would burn your skin). Before you make an appointment, ask the receptionist about their no double-dipping policy, Dorin advises, and keep an eye on your technician to make sure she’s using a fresh applicator every time she spreads the wax.
  3. Plucking with dull tweezers  Over time, metal tweezers wear down, and the surface that grabs the hair loses both accuracy and flexibility, which can lead to undesirable results, says Dorin. If hairs are starting to slip through rather than being grabbed by your tweezers, you can sharpen them by rubbing the edges with sand paper or a fingernail file, or outsource the project entirely by buying a pair from a company like Tweezerman, which offers a lifetime of free sharpening for their products.  
  4. Never cleaning your tweezers “Tweezing hair leaves your pores open to potentially harmful elements, like infection-causing bacteria, if you haven’t sanitized them before use,” says Dorin. Clean them with a cotton pad soaked in rubbing alcohol after each use to help remove build-up and prevent bacterial growth. Dorin also recommends storing tweezers away from other products that harbor bacteria, like makeup sponges and brushes (you’re supposed to clean those regularly, too, BTW).
  5. Picking the pointed pluckers Pointed tweezers can break off hairs instead of cleanly pulling them out of the follicle, leaving you with patchy results, or worse, painful ingrowns, says eyebrow specialist Sania Vucetaj, owner of Sania’s Brow Bar in New York City. Choose sharp, slant edge tweezers instead.  MORE: 4 Ways Your Brows Are Aging You
  6. Tweezing too often
 If you pluck your brows every few days, you run the risk of removing hairs you actually need to maintain shape and fullness—and the results can last anywhere from 3 to 8 weeks, depending on your individual hair growth rate, Dorin says. Over-plucking can also permanently damage hair follicles, meaning a wrongly plucked hair may not ever grow back if it is repeatedly tweezed. Tweeze once every 2 to 3 weeks so you can see which hairs actually need plucking. “It may seem scary to wait that long, but you’ll see that your brows do actually grow in and look better,” says Redmond. 
  7. Cutting hairs too short Super-short hairs can stand up at attention rather than lie flat, says Joey Healy, owner of Brow Lab eyebrow grooming studios in New York. Use an eyebrow brush to lightly brush brow hairs up, down, and in different directions before using brow scissors to snip any hair that seriously sticks out, keeping the chop to just ⅛ of an inch.
  8. Using a magnifying mirror and bright lights Super-bright lights and zoom mirrors make you lose perspective. “You’ll see more than the normal eye can see, which makes it easy to go overboard and thin out your eyebrows too much,” says Vucetaj. Instead, tweeze brows in front of a regular mirror in natural light; you’ll be less inclined to over-tweeze, since you’ll see your brows as they really are.
  9. Finishing one brow before you start the other Shaping one entire brow at a time can lead to asymmetry, since it’s easy to lose track of which hairs you’re taking from which part of the brow, Vucetaj explains. Pluck just a few hairs on one brow, then step back and look in the mirror. Repeat the same process on the other side, and keep alternating between brows to keep them balanced.
  10. Waxing while using a retinol
 Photo by Claire Benoist “Retinols make skin extra-sensitive and thin, which can lead to painful tearing during waxing,” says Redmond. If you can’t temporarily part with your favorite retinol product, Dorin recommends sticking to tweezing or threading. Also avoid glycolic, azelaic, alpha hydroxy, benzoic acids, and alcohol—common ingredients in exfoliating or astringent products—several days before a wax.
  11. Using your hair regrowth treatment to bring back sparse brows It may work wonders on your head, but experts agree its traditional liquid form and dropper application are not well suited for brows. “Minoxidil (FDA-approved to treat thinning hair) is tricky because the application has to be really accurate and applied with appropriate tools, or you run the risk of sporadic and uneven patches of hair growth,” Ostad says. A better bet is to use minoxidil in lotion form, which your dermatologist can prescribe, says Dorin. Or try coconut oil instead; it was found to stimulate hair follicles in a study from the National Institutes of Health, says Ostad. 
  12. Tattooing on your brows (yes, people actually do this)
“If brow tattoos looked fabulous and natural everyone would have them—but they just don’t look real,” says Healy. The ink is opaque and doesn’t mimic the light-reflecting qualities of real hair, and it can also change color over time, like any other tattoo. Skip the ink in favor of using a pencil or powder two shades lighter than your brow color for the most natural looking effect, says makeup artist Ramy Gafny. 
  13. Using an at-home bleaching kit to lighten brows “Conventional bleaches work by stripping out color from the hair, which can turn the hair yellow, white, or orange—not a look you want,” says Healy. Bleach can also be irritating to skin, particularly if you leave it on the area you’re trying to lighten for too long. If you’ve lightened your hair and want your brows to match, have them done in the salon at the same time. MORE: 10 Essential Makeup Tricks For Women Over 40