You dont need any tips, youll do fine. Ignore pretty much anything these idiots tell you to do and just go to school and talk and youll live. Seniors wont hunt you down in the hall and shove you in a locker like on TV.
The only tip I have for you is regarding your title, its "high school" - Remember that, because I lost a lot of points for "High School" or "Highschool" on my essays.