Advice/feedback for taking the GMAT?

[OfficerA]

My apologies all for how broad a topic this may be, but as I'm anticipating graduating from TESC sometime after February (when my last class ends), I was looking at tackling this beast next. I read a little about it and even found a site with study guides/supplies for it, but just how much of a beast is it, and how/where is the best way to prepare for it?

My plan, which is to continue on with my commissioning in the Air Force, is to proceed to SEMO's online MBA program, as the AACSB accreditation is required for the program I'm looking at. Part of the entrance requirements is the GMAT, which is why I'm going to try to get started now, although it'll be in the backseat somewhat as I test for promotion within the next three months. Still, at least I'll have something to look forward to.