I'd say something like: don't waste your time. It runs so fast. Don't keep grudge against somebody for a long time. It devastates you much more, than those you keep grudge against. Forgive people. They hurt you mostly because of their weakness. Learn as much as you can  as long as you are young. And finally, respect your parents. They are the only people on this crazy world, who will love you regardless anything, whoever you are and whatever you do.

Before you get angry with someone and open your mouth, think and count. It comes out better when you've thought about it and have had time.  Apologise if you're wrong.  There is always another point of view. Accept that sometimes things don't always go your way. Admit your faults and mistakes and don't repeat them.  Finally, never, never give up.

You're young. Enjoy it because it's amazing how things you take for granted now, become an issue when you're older.

Time waits for nobody.

Spend your time and money collecting experiences and memories and friends.

Take care of your neighbors.