1. Get a Clarisonic. Oh my god, doooo it. It's like a weird vibrator-shaped electric toothbrush for your face, and cleans 10 times better than your hands or a washcloth. I'm not getting paid to say this. Every beautiful girl I know has one, and also me. You'll never look back.

2. Cut the social fat. That one friend of your ex who's kind of boring but always wanted to have sex with you so he usually picks up the drinks tab? Stop texting him back. That former Goth girl from your high school who's constantly got baby pictures popping up on your timeline? Unfriend. Keep a core group close and drop the rest. Ain't nobody got time for that.

3. Stop judging your friend's dickhead fiancée. You may not have liked that she was dating a dickhead, but now they're engaged, and you are no longer allowed to be vocal about how much he sucks. She loves him. Maybe that is because he is a short, American Eagle polo-wearing warlock who cast a spell on her, but she loves him. Get them a folding chair from their registry on The Knot and keep your mouth shut.

4. Buy a full bed! If you haven't already. I slept on a twin bed until I was 24, and the day I got a full bed was the day I went from "not a girl, not yet a woman" to "kind of a woman, if you ask me on a day when I don't feel bloated." After four years of post-college scrimping, it is more than OK to start spending money on your quality of life — in fact, it'll improve almost every other area.

5. Stop not knowing when your period is coming. That is what the calendar on your phone is for. Put a regular cycle alert in your phone that is like, "I'm Bleeding. :D"

6. Not everybody has to wear foundation. Often we carry on old beauty routines for years (hello, L.A. Looks hair gel) without realizing that they actually might be unnecessary or even making our skin worse. No matter how bad your skin might be, slapping seven obvious layers of flesh-toned drywall on your face is probably not an improvement. Try BB cream or a tinted moisturizer?

7. Make the transition from talking shit to doing shit. Think about all the times you have moaned to a coworker about how unhappy at work you are or to a friend about how miserable you are with your boyfriend. We talk shit because it's easy, comfortable, and cathartic — but nobody will know, and nothing will change, until you speak up. You are not the Little Mermaid. There is no weird animated crab to communicate your feelings to the people in your life, unless there is, and give me one.

8. Invest in a black blazer. Dude! Zara has some good, cheapish pieces. That is where I got mine.

9. Date a type of dude you never would have dated before. Still single, and not by choice? Then the guys you were going out with were not working out for you.

10. I've said it before, and I will say it again. Stop worrying. Everything will work itself out. The best thing you can do for your future — or at least waiting for your future to start — is to breathe and stop being such an unforgiving asshole to yourself. Oh, and also the whole "not perioding all over your bed" thing.

Read the previous installment of Twilight: Breaking Womanhood: 10 Things Every Woman Should Know by 21.

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Got ideas for a list? Tweet us at @Cosmopolitan with the hashtag #CosmoGuidetoLife

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Anna Breslaw
Writer. Things I appreciate: Ghosts, white wine, men who look like they could protect me from predators, and a great homemade deviled egg. Also, I have a VERY ambivalent obsession with Sex and The City but I'm not like any of them, other than maybe Miranda's cat.