Most of the things I can tell you about ACing, you can read up on The Black and Blue, a huge blog for camera assistants answering almost all the questions you can think of. Nearly every part of the job is covered, including useful tips, insider information and video tutorials. The hours I spend reading on it helped me hugely to prepare for the role. The more time you spend reading up on that blog prior to your AC role, the better. Of course some things are only learned hands on, but your 1. AC and DoP will see and appreciate if you have prepared before hand.