Dr. Awkward said:
My advice to players is always this: go read a manual on improv theatre. Improv theatre is essentially dialogue written off the top of one's head using a few key concepts (sometimes provided by the audience). There are rules that have been developed to help make it work, because if you aren't any good at improv, you'll end up standing around like a doofus going "um..." while the audience snores.
The big rule I always double-underline is "don't block," followed by "yes, and..."
Don't block means that when someone hands you a hook, even if they don't know it's a good hook, you take it and work with it. When the DM says that a group of gypsy merchants are selling their wares, you decide your character happens to have spent time travelling with gypsies and knows some good stories to tell to ingratiate himself to them. Not only have you helped to flesh out your character to make him more interesting and realistic, but you've provided a good way for the DM to pass on rumours and other information that he might have wanted to share (with or without skill rolls, as the group prefers). You might then use the gypsies as a source of hooks that catapult you into future adventures. In essence, you're helping the DM by giving him a footing on which to build some interesting NPC interactions and adventure hooks. Blocking, on the other hand, is when you say no. When you decide you don't care about rescuing anyone, or solving any mysteries, or talking to any townsfolk, or when you want to be chaotic evil so you can sabotage the party for no reason. It's just bad form.
Yes, and... essentially this is the opposite of blocking. Not only do you want to take the hook, but you want to make it more interesting than it was. In improv, when someone says "I see you bought a new hat," you reply, "yes, and it's one of those new musical hats!" In roleplaying, when a plot hook wanders by, not only are you waiting to pick up on it, but you're also ready to do some work to make it your own. Not just grudgingly going off to rescue the princess because "it's what we have to do for the plot, obviously." No, your character wants to rescue the princess so he can marry her, regardless of what her parents think. Surely his charm and wit can win her over, and if he can get her favour, what must he then do to impress her parents? If you're the hack-and-slash type, maybe they'd like some exotic trophies to hang over the fireplace. If you're the deep-roleplayer type, perhaps just laying on the charm real thick will do it. There's a lot of room for multiple solutions to the same situation, but you have to try to arrange a situation before you can solve it. Maybe there's a rival suitor, or maybe the girl decides she wants to elope. Maybe she turns up pregnant and your PC is suspect #1. Suddenly it's not just a plot hook, it's a story with your character in it. It's more engaging, more interesting, and it'll end up being more fun.
This isn't about telling players, "It's my way or the highway." It's about telling players, "Look, we're in this together. We can cooperate and make a fun game for all of us, or we can piss off and do our own thing alone and not have fun playing a game with each other. I think that the former choice would be the better one." People who are playing the game to win, or playing to crush the other players, or playing just to be a nuisance (whether they know they're doing it or not) are not good players, and a book to teach them how to play might help both them and the people they play with by making them more like the sort of folks we'd all like to game with.