Hey Bluesteel705,
I'm going through the same process at the moment (allbeit from a different angle as I'm already a serving ranker). Get youself down to the local AFCO and ask for all the WSOp paperwork, it includes a guide to what the RAF are looking for and what the guys at OASC will be looking for in your interview. If you cant or they dont give you it, PM me and I'll send you a copy of all the stuff i have by post.
Good Luck!
Fantaman