Do as you're told.
Do all your homework.
Don't prat about in class, you need your teachers to give you high predicted grades to get to the University/College that you want.
Do plenty of extracurricular stuff like sport and/or music, no matter how much your peers mock you for it, because it will make you stand out in your applications. Plus, if you don't start doing it now, it's much more difficult to break into it at University or College because people have been doing it since when you can start now.
(and don't care about the opinions of you by people in your year, i guarantee by the time you all part ways, you'll realise that you were only friends with 99% of them because you had to see them every day).