i can't remember air law as i done it ages ago, but i do remember it being straight forward. I read the entire Trevor Thom book then looked at the confuser. as it was (to me) kind of interesting I remembered just about enough to pass first time.
i did the nav exam at a time way before I actually done any practical nav exercises. i failed first time, and passed once i took it after my QXC. i understand why i didn't pass first time, there are certain subjects that you would do better in once you have practical experience of it. same with RT - i just about passed the practical, however I reckon I would have done better if I had actually flown through a control zone, MATZ, requested special VFR and so on.
the most difficult imo? met. utterly boring - learning about clouds and precipitation. thank god the confuser helped me pass.