We all make mistakes—and occasionally, we make the same mistakes over and over again without registering that they’re mistakes in the first place. We’re the first to admit when we’ve made a beauty blunder, which is why we’ve rounded up the 101 most common beauty mistakes to spare you from having the same slip-up time and time again. We’ve learned from experience. Hair 1. You’re holding the brush wrong when you blow-dry. If you hold the hairdryer with your dominant hand and work the brush with the weaker, you’re not alone—but you are wrong. While it feels more natural to hold the larger, heavier item with your stronger hand, you.