Boys
Don't take this area of high school too seriously.
I realize that this won't make much sense in the thick of it but just know that your self worth is not measured by their perspective, it's yours that counts.
That's something I had a really hard time with.
Also, sex is another touchy subject. Please be responsible. When, where, how, and who are all very personal and private decisions and they are YOURS to make. If your only just starting high school then you must be what? 14? I don't want to preach, just be careful and stay safe.
Friends
Find yourself a handful of great friends.
The fact is, in a couple years, you won't know any of the shitty people or even the 'sorta' friends. The people who will stick with you through the years, even after high school, are going to be those two or three girls/guys that you can truly be yourself with.
High school is full of people who seem fake but like you, their just trying to figure themselves out and find their place so try not to judge, just try to find a few good friends that will enrich your life.
By all means, socialize. Diversify.
But don't forget the true friends that matter the most.
School Work
Don't pull your hair out.
Don't overly stress yourself.
It is JUST high school.
I don't know if you have plans beyond graduation day yet. I know at your age, I didn't, but high school is only a small portion of the long life ahead of you and it's not worth some of things I saw my fellow classmates put themselves through.
Do your best. Try to get the best grades you can and try to get the best aptitude test scores you can. ((I don't know where you live but here we take the ACT))
Honestly, if you give the academic side of high school your best effort, then your free to make whatever plans you'd like afterwards.
All The Other Stuff
Stay out of the big trouble.
Stay away from drugs and alcohol. You're going to be on the receiving end of a lot of pressure to try things you might not be comfortable with, but remember what I said earlier? A good friend does not base their friendship on whether or not you got s**t faced at after-prom. I know that sound very "after-school-special" but I'm not done yet!
If your anything like the me or my friends, then you'll want to experiment.
I'm in no way endorsing underage drinking but I confess, I got drunk a couple times in high school and I smoked more then my fair share of weed. I still do enjoy the occasional smoking session every now and then. I can't stop you from doing these things. I'd be a hypocrite if I said not to. But just do your experimenting SAFELY.
I hope this helps. Feel free to PM me if you have any other specific concerns. I might be able to help.
I graduated about two years ago... I know I'm so old... ugh.