I began by summarising all of my CPL theory books. I then moved onto "handling the big jets", "how to ace the technical pilot interview", "Captain XYZ guide to Cathay Pacific Interview (something like that)", "mental mathematics for pilots". That was all I can remember off the top of my head. My study was ongoing over a couple of months. Equip yourself with as much knowledge as reasonably possible. The study program I developed for myself was easily the hardest few months of my life, but it was completely necessary. There is no other way to get in, I can promise you that.