Which Service Should I Join?
Next, you'll need to decide which service you are interested in. Sometimes, you'll know this in advance. Perhaps you had a friend or relative who served or are serving in a particular branch of the military and you want to follow in their footsteps. You should give this matter much study. Each of the services are different, and some people may be more suited (based upon qualifications, temperament, and/or interests) for one service vs. another. Make sure you select a service that YOU are interested in joining, based upon YOUR interests. Don't join a service just because someone else liked it, or expects you to. It's your life, your interests, your decision. The article, Pros/Cons of Each Military Service may help you decide which service is best for you.
The Marines are, without argument, the most "military" of all the services. If you join the Marines, expect to eat, sleep, and breath "The Corps," 24 hours per day, seven days per week. All Marines are considered a "rifleman" first, and whatever other MOS (Job) they hold second. This is attributable to the high level of marksmanship training that all Marines receive. The Army is probably the second most "military." Many Army Combat Arms units, such as the elite Rangers, are just as intense and "gung ho" as the Corps. The Navy, while not as "rigid" as the Marines and Army, has many deep-set customs and traditions which are immobile. For the "gung-ho" sailor, the Navy possesses, probably the best-known special operations force -- the Navy SEALs. The Air Force, tied with the Coast Guard, as the "least military" service, also has it's share of "gung ho," in the the elite Combat Controllers and Air Force Pararescue forces. For more information, see Special Operations Forces.
(Note: Recruiters see lots of folks who want to enlist and serve in one of these elite fields. The truth of the matter is that most people who apply for the "elite" programs wash out due to the very rigorous training requirements. If you enlist to become one of these "elites," and you wash out of training, you don't get to quit. You'll be required to serve the remainder of your enlistment contract in a different job).
If you like shooting (a lot), and want a complete change of lifestyle, to include a deeply ingrained pride of service, commitment, and sense of loyalty, the Marine Corps may be just what you're looking for. This may be a minor point, but it is very telling: When you ask an airman what he does, he will respond, "I'm in the Air Force." When you ask a sailor what she does, she'll respond, "I'm in the Navy." If you ask a Marine what he does, he'll say "I am a Marine."
If you want a little more flexibility in your lifestyle, but still want a strong sense of being in the military, the Army may be for you. If you like to crawl through the mud and blow things up, using the latest and greatest of "blowing up toys," consider one of the Army's combat arms branches. You'll likely get all the time "in the field," that you want.
The Navy is probably the best place for those who like to travel -- a lot. There are few ratings (jobs) in the Navy that won't spend a significant amount of time at sea. This might be great if you are single, but might be something you'll want to think about if you have a family.