For you post-college fellers.
Once you have your degree (which is requirement #1)....
Active Duty: Contact the OFFICER recruiter in your area to get sheduled for the exams AFOQT, BAT, Officer interview, FC1, etc....
Reserve: Contact an Air Force Reserve recruiter in you area. There are now designated recruiters for Pilot/Officer hopefulls (I think). They are responsible for large territories, so be persistant. Hopefully the local Reserve recruiter can put you in touch with the Officer recruiter. The local recruiter may also be able to schedule you for the AFOQT and BAT, but I'm not sure now. The Reserve recruiter can get you scheduled for the AFOQT, BAT, and FC1. Once you get those items out of the way (you don't necessarily have to wait for the FC1), you should start hunting for units that you want to join. What worked for me was to look up Reserve bases and squadrons on the AFReserve website or on Baseops.net (aviation jobs listing), call the main base number, and ask for the Pilot's Section or Pilot Scheduler or Chief Pilot for the XX Airlift Squadron. Once you get in touch with them they will tell you what sort of stuff you need in your package and where to send it. If you package is good enough, you will be contacted about an interview. Then if you do well on the interview, and you are selected, you will receive sponsorship for the national Reserve selection board. Note, you can also go unsponsored to the national board, but you have a better chance with sponsorship (nearly 100%). Also, if you are selected as unsponsored, you must then shop around to find a unit to take you (same deal as the other, package, interview, etc...) before you can begin training. ATTENTION: If you have a particular unit or units that you want to get into, take the time to go and visit during a drill weekend when there will be lots of dudes around. This will help tremendously for obtaining a UPT slot. When you contact someone from the unit, make sure to ask about visiting.
Guard: Call a nearby Guard base and ask to schedule the AFOQT, they should be able to hook you up with that as well as the BAT. I'm not too current with the Guard info, but it works very similarly.