I haven't got much to say about identifying faults, but I included this page anyway because identifying faults is clearly an important topic. You can find plenty of detailed guidance in section 4 of the society's handbook. I suggest you read it now if you haven't done so already.
Reading the handbook you could easily come to the conclusion that faults are easy to find once you know what a fault is. I find that sometimes things that are actually not that clear-cut. I have to exercise my judgement in what "faults" I record or take action on, in order not to waste my time and other people's time by pursuing matters that are unimportant or are unlikely to result in any action. That judgement comes only with experience. I got a few things wrong at first, and I'd be surprised if any inspector didn't.