I would do your homework. Talk to people, get on the internet, etc. Get all the information that you can BEFORE seeing a recruiter; some are honest and some are not. Find out about the jobs - the good, the bad and the ugly. Decide whether or not you want to be on ships or subs, etc. My personal choice would be Navy or Air Force, but each person must decide that for themselves, after doing the research. I was in the Navy for almost 9 years. I do not regret it. As most have said, it will NOT get you away from the immaturity. I was 23 when I went in, and I was one of the older ones. However, that was 15 years ago. I would have retired if I had not married and had children. I wanted to make them my priority.
I went into the reserves first, then when I decided that I liked it I changed to active duty. That gave me a chance to see what it was like, and whether or not it was for me. Note: I went during a time of "peace" not a war. That will make a difference. The military is not for everybody.
They have programs that can help you with school. They will help you finish, then you serve as an officer for a certain number of years. Again, do your homework. I would not depend solely on the recruiters for information.