I went to the U.S Air Force Academy and got commissioned through there. You can either go that route, enlist, or do ROTC. You have to be drug free and motivated, there really is no interview process.
I applied through a recruiter. The process took 9 months. I interviewed at US Air Force in Mar 2014
Interview
Met with a college recruiter at a career fair for the Palace Acquire Program and was highly recommended for a couple of positions. Interview was a phone interview conducted a couple months into the start of the new year before a panel of people I would be working with. Offer was sent 2 days later.
Interview questions [1]
Question 1
None, all questions were regarding previous experience, leadership, teamwork, etc.
Know or have an idea of what you want to do for at least the next 4 years. Don't let a recruiter try to snowball you into something that is not possible. If it sounds too good to be true, it probably is. Find someone that has served or is currently serving and ask them for advice.
Interview questions [1]
Question 1
Dont lie to the recruiter, they will find out way down the road, fraudulent enlistment is not a way to end a promising career