You should have a sound understanding of your basic Engineering/Physics theories - you will stream (Mechanical or Avionic) therefore have an idea of which way you want to go - whilst in the AF look for every training opportunity going, either internally or externally and don’t be scared of dipping into your own pocket to get better qualified because one thing is assured If you go in you have to come out...so be prepared and there are a lot of people trying to do that!!! See
HERE - Good luck