I applied through a recruiter. The process took 4 weeks. I interviewed at US Marine Corps in Mar 2012
Interview
If you decide that you want to join you can speak with a recruiter. After you go through that entire process you will go to take tests and what not. If you physically and mentally meetthe requirements you will receive a date for boot camp and select an MOS dependent on what you scored on the test. After boot camp you will receive your duty station and begin your actual job.
I applied through a recruiter. The process took 2 months. I interviewed at US Marine Corps in Apr 2012
Interview
To join you must first meet the standards: have a high school diploma or GED with 15 college credits and meet ht/wt standards. Then you must take the ASVAB and this will determine what jobs you qualify for. Once completed your recruiter will tell you what jobs are available and what they consist of. Make sure the job is something you like and a job where you can get promoted at a decent rate. Some jobs offer bonuses and there's also an early shipping bonus (don't let them lie to you and tell you there isn't).