Do a sport, join a club, don't just go to school then go home and play video games. You have to study a decent amount (depending on your classes), but you'll have a much better time if you do something extra curricular. I decided to wrestle my freshman year and it might have been the best decision I've made in my life up to this point. Talk to people, make some friends. High school is 10x more fun if you aren't a loner. Don't hang out with the wrong crowd. Try new things (just no drugs lol).
I'm going into my junior year next year and this is what I would tell myself from two years ago.