First of all don't rush to grow up... you won't believe how suddenly time flies by and you find yourself buying anti-wrinkle cream!!!
Take it a step at a time. Your main concern at the moment should be getting the best grades you can in school and continue studying for as long as you can as once you leave school its really hard to find the time and money to study again.
Learn how to be independant and responsible. When eventually you start working go for customer orientated jobs which will help you be a people person. Have a work experience before going for this line.
Being 21 or over would make the job easier for you as it has a lot of responsibilities nowadays.
Studying nursing or managment would be helpful.
Take it step by step enjoy being young and make the most of your teens and see what's on offer when you feel ready to go for it. Good Luck!!