Re: question for those in the military
There are about a million and one routes to go. You can go college first, enlist first, go reserve, go ROTC or PLC (Marine Corps). I would also suggest the Officer route, but for it being so early for you I would do as others here have said: work your tail off in school, take hard courses (challenge yourself in anything you do), take a personal vow to better yourself in every way, do the right things in society, and be humble about all of it.
If I could do it all again, I would go directly to college after applying for an ROTC scholarship, if you get it, you can still drop the contract after a year and still have that year payed for. If you don't get it, go to the year of college and train with those who think highly of themselves, the humble scholars and life-long learners. If you decide to go the enlisted route after a year because Officer life isn't quite for you yet, then go for it. But then at least you haven't screwed yourself out of an absolutely awesome oppurtunity. I can speak towards the Marine side of the house, and Navy too I suppose, but as for Army, my knowledge is slightly limited. Air Force.... I haven't a dang clue what they do.
Stay motivated, and never quit. Take pride in what you want in your future, you'll see your friends failing at what they do right out of high school. You don't have to associate with those types of people. Develop a personal identity of 'Future Military Service Member', and don't let anything or anyone say you can't get it.
I will now step down from my soapbox.