The first day of high school is pretty easy going, though expect some homework due the next day. Just keep a planner, I 100% would not have made it through all my classes if not for my planner. High school wasn't as terrible as everyone cracked it up to be, so don't go into your first day with an "oh this is going to be tough" mindset. Trust me, it will not be the hardest thing you'll go through in life. Also branch out; try to talk to other kids you normally wouldn't talk to if you want, that way you find your 'group', the people you're most comfortable with. Other freshmen like yourself are all worried about the same things you're worried about, so just know you're not the only one feeling the way you are. Honestly, my high school experience wasn't that spectacular, I don't really have any fond memories of the place, and I especially don't have a single negative memory. But believe me, great memories will come in college.