After lurking the boards for a while I have realized that the best I can do to prepare isn't much. I too was trying to figure out the inboard outboard stuff, and attempting to get my hands on one of those gouge books.
I remember reading somewhere, on these boards maybe, that OCS is basically like a stream, hop in and it will take you to the other side, so long as you do not give up swimming and drown.
I will, however, familiarize myself with a bit of marching (my Father and Grandfather both were prior military and will give me a few tips), learn how to iron well as I'm terrible at it, and PT like mad (mainly to work on form as best I can). I feel that's about it until my recruiter gives me some more information once I am accepted.