1. People will promise not to leave you. They will. It's okay to be sad when they do.

2. It's always okay to cry. Find a bathroom, bury your head in your pillow, and let it out. Cry in the shower. Cry in your car. Cry when you need to.

3. People will flirt with you, then ignore you. Then they will flirt with you some more. It will be confusing, and you will have every right to stop putting up with it.

4. Pay attention to what people say when they're angry. When you make up, they will tell you they didn't mean it. Know that they did -- but know that they wish they didn't. Forgive them.

5. Never pretend to be someone your not. If you don't like classic novels, don't act like you do. If you don't want to wear leather jackets and combat boots, don't wear them. You will lose yourself trying to be someone else, and it will be difficult to come back.

6. People will be mean to you. They will call you names, spread lies, and talk about you behind your back. Eventually, you will realize it's petty and stupid. You will be right to move on.

7. Your friends will not always be there for you. When you really need to talk, they will sometimes not want to hear it. That's okay. Take a deep breath. Remember all the times you felt the same way.

8. You will wait and wait for your first kiss, your first date, and your first relationship. The anticipation will kill you. You will keep trying to find the right person in everyone you meet. Relax. The best things happen unplanned.

9. Enjoy being young. As you get older, things become more and more scheduled out. Love that you aren't there yet. Enjoy being spontaneous while you can.

10. Tell people how you feel. It will be terrifying in some cases and liberating in others. It will create relationships and ruin them. Speak your mind always.

11. Sleep.

12. Talk to people. Learn things from them. Always carry $5 and a lighter. Be prepared for the opportunity to get inspired.

13. Always bring a sweater -- even if you think it won't be cold.

14. Try new things. You never know what you might end up loving.

15. Take care of yourself. Wash your hair. Make smoothies. Eat vegetables. Drink water. Go for walks in pretty parks. Take care of your body and your soul, even if they refuse to take care of you back. Remember that your body is just the seatbelt in your car, but it's important that all the parts are working.

16. Stare at yourself daily. Take selfies. Take inventory, and each time compliment something. Maybe today you love your hair, but don't like the curve of your lips. But tomorrow -- tomorrow you might think you have a cute smile even though your hair is a mess. Find something to love about yourself.

17. There will always be someone prettier, funnier, smarter, more athletic, or more popular than you. The beauty of it is that it isn't a competition.