Hiya, good to see you!
At least from my personal experience (as a kinda socially awkward nerd), my tips for high school would be "don't be afraid of talking to different people and making friends" "if your friends suck and start treating each other badly, don't be afraid to leave them" and "if you do leave a group of friends, don't be scared to try and find a new group".
I say this because I left a friend group who were treating each other badly, but I didn't make new friends until I moved schools and spent two years being sad and lonely. To be fair, making friends was kinda difficult, but there were people I probably could have befriended if I hadn't been so apprehensive about it.
Also: try not to get too caught up in people's drama, it never really turns out well. Teenagers can have drama over a lot of stupid things.
On the academic side, pay attention in class and try and keep on top of assignments and things, but it's ok if you don't put 100% of your effort into your schoolwork - good grades in high school can be helpful but they really don't make or break that much of your future. I did not take this advice (or at least I understood it conceptually but could not bring myself to do it) and I was very stressed in my last few years.
