2. Kill Off A Major Character
It doesn't sound very productive, does it? But it would have definite long-term benefits. So far, none of the individual villains have really posed a huge threat to the heroes. Iron Man has faced armoured foes that were very similar to him and an Extremis-empowered foe who you can't help but think that he could have just blasted the hell out of from afar, Hulk has gone up against what was essentially another Hulk, Thor faced his own brother, Captain America faced another super-soldier and the Avengers collectively faced an army of individuals that Black Widow could defeat in hand-to-hand combat... whilst we were expected to believe they were a threat to the likes of Thor and Hulk. We haven't yet been made to feel that the heroes were in any real danger, so have a villain show their might by killing off someone which, in turn, will also show that Marvel aren't afraid to kill off a major character. Doing so will add excitement and ensure that audiences will be on the edge of their seats far more in future movies. On a strongly related note...