If you mean you're going to study abroad in an American high school, my advice would be to join as many extracurricular (activities at the school, but after school ends) as you can! Even if you are not completely fluent in English, the American students will like you just because you're foreign ^.^ They will help you learn! Don't be afraid to put yourself out there in situations that may be unfamiliar, it is the best way to learn in a new culture. Make lots of friends, too! (They will help you with class work and teach you more language and culture). Talk a lot, people won't make fun of you if you mess up words sometimes. Talk to your teachers a lot too, they more they like you, the more helpful they will be in class :) If there's anything else you'd like to know, feel free to ask! I am an American high school expert, having attended one for 4 years =P Good Luck!