The best advice that I was given for a game had to do with what to do when you have taken a break in the campaign. The advice wasn't for any game in particular. At the time I was GMing a Pathfinder campaign and we were playing sporadically. We hadn't played in a while and I was listening to a podcast (I can't remember which one, maybe Haste) and the advice they gave for starting back up a from a break was to start with some action. They said to start with the players in the middle of a fight or some other exciting situation and that would get everyone back into the game. I tried it out at it was a success!