You are embarking on a great quest...and man I wish I started when I was as young as you. There are about 4 million pieces of advice that I could send your way, but let me tell you the most important: don't get in trouble. There are a ton of ways to get into the service and fly jets, but they all start to fade away if you have problems in your past. That is not to say that you can't get in if you've got a record, its just to say that it is harder.
And, of course, surprise, surprise, the guys who stay out of trouble also get the best grades, do the best in sports, etc...
For now, just arm yourslelf with as much information that you can...the rest will come with time. Also, check out this website (
http://www.fighter-pilot.org). It has a lot of great info to get you started. Get ready to be drowned.
Keep up the good work!