AFROTC det commander here. USAF offers some very good programs to go enlisted to officer.
The best source is your base education office. They've got all the info on all the different programs.
OTS is one route. It's tough to get in. Especially looking at this next year, they're significantly cutting the number of beds available at OTS to reach authorized USAF end-strength, so there'll be much fewer slots available to the same (actually more, given the state of the economy) number of people competing for them. Your prior enlisted experience will help, but they're essentially taking tech degrees (chem, physics, math, comp science, and most of the engineering disciplines) and nursing degrees, and that's about it. If you've got a poly sci degree, your odds are pretty low.
There's (IIRC) three other routes available to active-duty airmen. All three involve some form of separating and going to AFROTC.
-AECP is where you stay active duty, but your "job" is to go to school. You appear at the local AFROTC det once a month in uniform (and every duty day during breaks) but otherwise you're in class like any other college student. You still have to meet physical, grooming and retention standards (no goatee, sorry). Once you graduate, you're off to OTS. AECP also leans heavily towards the engineering degrees for selection.
- NECP––same concept, but specifically for nursing degrees.
- ELA (formerly the Bootstrap program). You take a two-year leave of absence from the USAF in exchange for getting your degree. You get base pay but no allowances (BAH, BAS, etc.) and earn a two-for one active-duty service commitment (for every year you're gone, you owe Big Blue two). You also don't get additional tuition/ed cost assistance––you either use GI bill, or student loans/robbing banks.
Or you could completely separate, then apply through OTS or local ROTC detachment for admittance. In all honesty, ROTC is the way to go; your odds are much better than OTS and it's pretty easier for a prior-E to rise above the ranks of the fresh-out-of-high-school cadet who still can't find their dorm room two out of three times.
Hope this helps. Once again, go to the base ed office––they've got ALL the details, plus how to apply for these programs.
Good luck!