From what I learned during those years:
-Join clubs, play sports, or do community service because colleges literally get hard ons for applications that have a decent number of them.
-You will go through changes so don't be surprized if you find yourself liking something one minute and absolutely hating it the next. Depending on your personality, this could also include people. Some of your friends will probably stop liking the same things you like and some will flat out just become pricks. Don't be surprized if some of your friends who used to play Pokemon with you in elementary school think you're a dork because you still like it.
-There's a good chance that you'll go through depression at some point in high school. If it gets bad enough, definitely seek help or you'll miss out on a lot.
-Do your best but don't burn yourself out. Seriously, as a senior in college, I've seen this way too many times: you have a 3.7-4.0 GPA all through out High School, you're a member of like 4 different clubs/sports teams, and you have a full ride thanks to scholarships and then, BOOM, freshman year of college you're so burned out from the sheer volume of stress that all you want to do is smoke weed, play WoW, and eat Doritos.
-Keep a good relationship with your parents because this will probably be one of the biggest things that will help you out when you hit a snag especially in your college years. Having a bad homelife is pretty much a continous downpour of suck and will cause noticeable differences especially when you start to do things like driving and dating.
-Chances are you won't marry your high school sweet heart; get over it. If you don't get laid or even have a girlfriend by the end of your senior year, it's far from the end of the world and should hardly be the main focus of your high school years.
-If your school has a work program or dual enrollment program hosted by local colleges, take them because they will make your junior and senior years considerably more tolerable. Also with the dual enrollment program, you'll have a jump start on college so not only will you get some credits out of the way but you'll bypass that awkward freshman stage where you continously look inept and ********.
-Start saving. From all the money I saved while working my high school years, I was able to afford my first car and two trips out of the country (one to Japan and one to England) during my freshman year of college. Also getting a job and having some job experience will help you during the long college summers as employers will generally point and laugh while they send you away or give you the worst positions if you don't have any.
-LEARN TO TYPE IF YOU HAVEN'T ALREADY!!! I cannot stress this enough because college work will literally **** you if you don't. Seriously, if you can only poke at the keys and have to right a 15 page term paper, you'll pretty much wish for death. The sooner you learn how to the better because, at first, it's a huge advantage.
-Big, possibly life changing, things will occur in your high school years. You may have a long time friend move away. You may have a long time friend die. Your parents might get a divorce or some of your siblings may move out of the house. Although these exact events may not happen, just be aware that virtually no one slides through high school unscathed.
-If she smokes, she pokes but she probably has gonereha too. I hate high school gossip but if you want to avoid the chick who was plowed by the football team, men's choir, and chess club all in one night, you may want to open an ear to it. Despite the nature of gossip, it's sometimes actually somewhat worth paying attention to, to avoid making the REALLY stupid choices that will wreck your life.
-Get a good book bag and take decent care of it. I'm a senior in college and I still have the same bookbag that I've had since my junior year of high school and it's been with me to 6 different countries. It'll really come in handy if you end up going to places a lot and crashing on friends' couches. Don't think of it as just a book bag, think of it as a portable suitcase.
-Stick with your friends from middle school (if they transfered to your school) and then work off of that to meet new people. Networking is amazing and the world really begins to open up because of all the new oppurtunities you're presented with. In college, it's about 10x more useful so get a good handle on it now so you don't end up as that guy who sends random friend requests to people on Facebook.
-Be aware of your habits and try to get a handle on them if you can. For example, if you find yourself downing a case of Mountain Dew in only a few days and your metabolism suddenly slows to a crawl, you're going to be SOL. I see way too many people in college that have little habits that have become big problems because they didn't deal with them early enough. This can encompass a lot of different things from being a compulsive liar to overeating to doing everything at the last minute to falling face first into abusive relationships.
-Try to befriend at least one teacher because having their perspective on things will generally teach you a lot. I'm still friends with my Junior Cooking teacher and I see her twice a semester despite graduating four years ago.
-Ask questions and do research even if it's over stupid and random stuff. It may help you land a job or have an interesting coversation along the line. I'm pretty much an encyclopedia of useless knowledge but it has lead me to meeting a lot of great people over the years.
That's all I can think of right at the moment.
