When you’re playing a game where there’s no GM throwing plot at you (e.g. Fiasco) or where there is, but they are leaving you, the players, to decide what to focus on (e.g. Apocalypse World) or indeed, where there is but they aren’t creating plot per se at all (any sandbox game), the role of players is different to your traditional GM-as-plot-provider game. And you have to do different things to make those games fun. Things which might even be considered antisocial in another game.
What I’m talking about is having an (in character) agenda. Your character should be up to something. They have at least one thing that they want, and not just in an abstract “fleshing out my character” way, but in a concrete “this is what I’m going to do right now to get it” way.
Fiasco is a perfect example because the entire drama comes from your stupid, short-sighted, out-of-control characters pursuing your goals. The game even forces at least one of you to have a game-generated Need! But it still needs the oomph from the players, the drive that makes the game tick. You can’t be sitting back and fading into the background in a game of Fiasco! Or rather, you can, but you (and the other players) may not have as great a game as a result.
Now I want to be clear here, I’m not saying that you should be constantly pushing your character’s agenda Out Of Character. When it feels like you can’t turn around for character X getting up in your face trying to do their thing, that isn’t fun. Your character is up to something, yes. You, on the other hand, are up to something else – trying to make sure everyone has fun, hopefully.
Fiasco and other “GMless” (or GM-light) games throw the spotlight onto the players in a way that can be a lot of fun. If you’re pushing your character into action to get what they want, while leaving space for the other players to do that for their characters, you’ll get a lot out of these games.