First, I commend you for wanting to join the military! However, as others have already said, make sure you know what you're getting yourself into. Yes, it's nice to have money for college, and you get some nice benefits (the medical is great to have, even though sometimes it's horrible!), and you have a steady paycheck that's always pretty much the same amount.
But it's not all fun and games! You may get sent to a foreign country, whether peacefully (Germany, Korea, Italy depending on the branch you join...) or for war/peacekeeping (Iraq, Afghanistan...). Consider this carefully. You can't just up and leave any time you want, and you can't give your two week notice. Also, even if you serve the minimum (I believe it's three years) you can still be called into active duty within three years after that.
The military is great, but like any bureaucracy, it has its flaws. Sometimes you'll have NCO's who have the intelligence of a rock, and they're not always the most kind-hearted people, either. You'll have to deal with people treating you differently (sometimes negatively), and you'll see a whole new side to the world.
I'm not going to discourage you, but it's important that you're realistic about this. Yes, you'll get money for college, which is great, but it's not money for nothing.
As others have said, make sure you join for the right reasons. Do you want to serve your country? Can you survive on small amounts of sleep? Can you handle firing a weapon? Are you willing to go into war even if you disagree with the reasons? Are you willing to risk your life for those reasons? Will you give it all? Can you handle being pushed to your limit physically, emotionally, and mentally?
Just think about it before you join, because as was said already, if you join for the wrong reasons, you're going to hate it. Then where will you be?
Good luck!