If you decide to join:
Coast Guard > Air Force > Navy > Army > Marines
Do well on your ASVAB, pick a technical job, sign up for all of the retirement services available, save up your base pay, don't do anything stupid or illegal, take classes while you're there (its free), go to networking events, make sure your papers are in order for the GI Bill, check out Yellow Ribbon programmes at different schools, check out the Reserves as well nearby where you think you'd like to go to school. Keep your nose clean, and in 4 years you'll have a full ride + books and room/board paid for, w/ a VA home loan, and retirement savings in your pocket.