homework
Always do your homework the night you get it, so it doesn't build up.
If you're falling behind, then don't go out at the weekend until you've finished it all, even if it takes you until Sunday night.
Don't phone a friend if you don't understand - talk to the teacher! They will explain it better. Always make sure you get what to do and write it down, if you don't get it all, ask the teacher to repeat it!
Punish yourself if you don't finish your homework. Say don't go out at the weekend, or no TV or something. Homework come before leisure!

classes
Try to enjoy them! If you don't, don't coast it 'cause you will suffer in exams, just do your best and try to get on.
If you don't understand the work, talk to the teacher! They can give you extra help or explain it some more. If you're really struggling, get a tutor!
When you chose your classes, CHOSE WELL! Don't chose them 'cause they sound easy, 'cause chances are, they're not. Art and drama etc. look easy but they're hard and you get lots of homework anyway. Make your priorities the subjects you're best and and enjoy most.
If you don't know anyone in your class, then make new friends! If you don't like them, find people you haven't spoken to and make friends with them! I love it when you don't know anyway 'cause you can make even more friends!

friends
Make as many friends as you can! In classes and at lunchtime etc., the more you have, the happier you'll be! Just talk to them, say hi, smile, call them at night to talk etc.
If you fight with your friends, then just apologise and move on. If they don't accept your apology, just hang out with other friends. Even if it wasn't your fault, fighting can make you miserable and it takes two people to end a friendship!
Don't bitch about your friends! If you do, they won't be your friends much longer. And people won't trust you.
Don't bitch about people you don't like to people who do like them! They'll tell them and it can get nasty (I speak from experience!)

teachers
If you don't like the teacher, TOUGH! Just try to do your work on time and stay on their good sides. If you don't, just carry on and talk to someone if it gets out of hand. Just avoid them in corridors but don't skip classes for their lessons.
Try get on their good side at the beginning of the year and it'll be fine. Just do you homework, answer a few questions in class occasionally and it'll be fine.
Don't skip school! You'll have to catch up and you might miss something important, and if you're caught the teachers will REALLY HATE YOU!!!

appearance
If you have a uniform, then make sure it's worn correctly, it's not worth the hassel getting in trouble - you'll look stupid, not cool.
Don't follow uniform trends.
If you're allowed to wear make up, don't overdo it for school, 'cause then you'll have to wear even more on occasions you're meant to wear make up, and look slutty.
Wear discreet make up, or natural look, i.e. no eyeshadow, but foundation (if you want), black or brown or clear mascara, clear/nude lip gloss.
Wear clear nail varnish if you have a uniform.