Remember that the course is designed to teach you how to teach. You are assumed to know all the background info, P of F, met, nav etc. There isn't really time on the course to cover this again.
Be able to reproduce the diagrams for the commonly covered bits of the above subjects. Unfoutunately the tick in the box format of the licence exams doesn't really promote understanding of the subjects, as opposed to just choosing the right answer.
In the air, be able to fly the more demanding exercises like EOL's, advanced autos, advanced T/O's & Ldgs & limited power (and know all the numbers) so that you can do them without having to think about the procedure. Otherwise, it is difficult when you have to think about what you are "pattering" as well as flying the aircraft.
Lastly, to get the best out of your FIC instructor, don't be afraid to ask if you don't understand something, but better to do this on the ground. Time in the air is tight.