Should I Join the Military?
First and foremost, you should decide if you should even join the military. As I said, the military is not for everyone, and some people find that out too late. Ask yourself why you want to join the military? Do you need a job? Do you want to serve your country? Are you thinking of making the military a career, or just do a term or two? Is it for the college benefits? Is it to learn a trade? Do you want to travel the World for awhile? Just need some time to "mature?"
Before you join, recognize the fact that a stint in the military is not civilian employment. It's not just like having a regular job. You can't just up and quit anytime you want to (See article, Getting Out of the Military). You can go to jail just for being late for work. (Granted, it's unlikely that a commander would impose nonjudicial punishment, or court-martial action the first time you are late for work, but it would be entirely legal for him/her to do so -- See Article 86 of the Uniform Code of Military Justice (UCMJ).) No matter how high your rank, no matter which service you join, there will always be someone telling you what to do, and when to do it. Many times you won't like or agree with your orders, but you take a solemn oath to "obey the orders of the President of the United States and the lawful orders of those appointed over you." Disobeying those orders can have serious consequences. If you can't live with this simple fact, save yourself and the government some valuable time and money, and don't enlist.
In a civilian job, if you don't like your boss, or don't like the job, you can simply quit. Not so, in the military. I get email all the time from recruits who just graduated basic training and/or technical school (job training), asking how they can "quit" the military. The short answer is that you can't -- unless it is for a valid hardship reason (i.e., someone in your immediate family is terminally ill, and your presence is required). The military can throw you out for several reasons, but you can't simply quit because you don't like it. If the military decides to throw you out (discharge you), the consequences of the discharge (depending on the type of discharge you're granted) can follow you the rest of your life.
If you like to smoke a joint once in a while, don't join. The military uses random, no-notice urinalysises, and -- if you're found positive, you may very well go to jail (as well as being discharged). The DOD urinalysis test can find THC in your urine for three weeks after you've smoked a joint.
The military is allowed to discriminate by gender. If you're a woman, know that there are some jobs and positions which are not open to you (most in the Marines, fewest in the Coast Guard -- in fact, all ratings are open to women in the Coast Guard).