Same rules as prison: find the biggest dude and knock him out to assert dominance as the Alpha.
Jokes aside, there is a lot of bad stigma associated with High School. However, more often than not, 90% of it is just drama. I find that the best [serious] tips to keep in mind are:
1. For the love of God, apply yourself and be all that you can be.
Don't make the mistake of just "passing" through High School. There are those that claim that it won't have the same sort of impact down the line as College/University will, thereby making it "insignificant" in the long run, but it will definitely influence your willingness to be all that you can be in life once you're recognized as an adult. Not to mention those grades open several doors to an assortment of institutions. Which leads me to my next tip...
2. Take this opportunity to decide your career path- what really interests you?
Some can argue that this point in time is too early for this wheel to come into motion, but I personally think it to be the best time. There are an assortment of classes/electives to choose from, and I definitely recommend dipping your toe into as many as you can to really solidify that particular subject that really interests you.
Once you find an area of expertise, start looking into careers early; that will allow you to really set-up a path to success in terms of what you should be aiming to achieve [grade-wise] in order to meet those goals.
3. Don't pretend to be someone that you're not just to "fit in"
As someone who has personally made poor choices in terms of who I hung around with during High School just for status, I can't stress this enough. Be yourself, and hang out with people who don't just take you for granted. The friends you want are the ones who respect you as much as you respect them. Don't hang around people who consistently bring you or others down, otherwise you may find that you'll pick up on their traits and behaviour without even knowing it. Hang out with people who have similar interests, and don't try to impress the "bad apples" by stooping to their level. There actually are selective groups (eg. the "cool" kids, geeks, stoners, etc) so dabble in each of them as best you can, but again, try to avoid the bad apples.
4. Have fun!
Seriously, High School is a pretty sizable pit stop on the highway of life. Don't miss the opportunity to make some great everlasting memories by having a good time. Remember that while it's important to keep your grades up, it's just as important to make the best of your High School years.
And just for shits and giggles, here are the essentials:
Walk on the right-side of the hallway and don't freakin' stop for NOTHING
Familiarize yourself with the school layout. Nothing worse than being late for the first day of class
Familiarize yourself with your timetable for classes. You do not want to walk into the wrong class, especially if you're late
Keep. Separate. Binders. I'm serious, don't cram all of your shit into one binder/folder because if you lose that shit you're donezo.
Expect heartbreak if you're going to be dating. Yes, young love is a thing in High School and holy hell is it full of drama. With that said, it's best to expect that things won't last forever (if it does, good for you!) and to understand that it isn't the end of the world if you're the dumper or the dumpee
Try not to conform to some image. Seriously, once you're out of High School you'll realize how stupid it was to buy a new wardrobe or act the way that you did just because you wanted to fit in. Save yourself some time and realize that none of it matters. High School is a whirlwind of insecurity, and everyone will be trying to keep up with appearance or behaviour when you really ought to just be yourself. The sooner you acknowledge "who cares?" the better.
I won't lie, I tried not to make this a long ass post, but once the faucet was on I couldn't stop it from flowing.
TL;DR - Refer to bolded headers. kthx