My record on AAR's is pretty bad, but I've learned a few things, you want to type things down as you're running through the game, specific details can be gleaned from the event log, but what you should be recording is thoughts you have about whats going on from the perspective of people involved with the action. Your own thoughts at least are a must, if something unusual happens, or you make a prediction that may or may not happen later, make a note of it and incorporate that into the thoughts of someone else who was in a position to make that call, or at least someone with that knowledge to pass the information along.
Or write up the AAR as things occur, later going through it and the event logs to get the more dry details.