Thanks. I also thought the first retest was after 30 days, but both the test itself and the LT administering it told me 90. For the record, after reading some more threads here, I am not going to retake it. I didn't really have a good grasp of what the typical score range was when I took it.
Anyway, things that helped me... well, my preparation was the Peterson's Armed Forces Officer test book, and this website:
http://manlypat.files.wordpress.com/2009/07/astb_study_guide.pdf
The Peterson's book isn't just for the ASTB, and it's not helpful at all. I wasn't even sure if the practice questions were relevant for the ASTB instead of the other officer tests. I wouldn't go that route. Buying a prep book was just the first thing I decided to do.
I wasn't concerned about the reading section, it's always been my strong suit. I'm honestly not sure how a person would study for that, and I don't think the sources I mentioned would be helpful. So, my concerns were math and mechanics. I just spent a couple of nights with the information in the PDF I linked and learned how to do math again, and learned the mechanics that were included in that PDF.
Results: I re-learned math well enough to get any normal problem right. Of course, with the progressive test, stuff got pretty insane, so I'm sure I missed some of those. What I thought was the problem was that I couldn't do the math fast enough. However, the new test isn't a time crunch--but the test itself doesn't tell you how many questions there are, and you can't go back, so I thought it was a time crunch and abandoned questions I didn't think I could get in 50 seconds with lots of time left. Don't do that! You have tons of time now.
Mechanics--that packet just isn't enough. There must be a lot more material out there.