If you could write a note to your younger self, what would you say in only three words?
I had two thoughts. 1) Words can hurt. 2) Try your best.
What would your note say? 
You've got this.
OR
Keep on fighting!
It'll be okay. You'll make it out in the end, even if you were burned. It will be a right.
Keep youre head.
Goes with keeping your head high or keeping it straight. Growing up (well actually up until just about a month ago) I would think irrationally. Just about as much as any other person that was under a lot of stress. I wish I wouldve kept my head straight and kept moving forward instead of stopping or moving backwards. I also have struggle with confidence like most young adolescents a few years ago. Slowly but surely I have gained confidence by then. I just wish I had someone to tell me to "keep my head high" earlier.
Run from them; don't trust anyone; don't get drunk;
Don't date him.
Don't give up.
Don't be naive.
Love yourself first.
Just Keep Smiling 
It gets better.