First off, congrats for entering high school!

I'll be a senior next year, and there are tons of things I wish I did when I was freshman. I wish I had joined a sports team or something similar. While I'm involved in tons of academic clubs and such, lots of colleges like to see you involved in sports!

Enjoy yourself, have fun, and stay out of trouble! Next year will be one of the best years of my life, excluding my difficult schedule (ughh, I think I'm going to die.. hehe), because I'm going to live it up. However, I'm going to stay true to myself, because I don't drink, smoke, etc. I suggest you do the same. Keep your grades up, even if you think "ah, it's freshman year, I can slack off". Nope! Doesn't work, you need to maintain it all the time! Get PLENTY of sleep every night if you can (it's been impossible for me my past 3 years because of my workload) so you can stay awake during classes and not get sick.

Most important, HAVE FUN!!! Don't stress out, it won't be bad at all! You'll have a blast, so be yourself!