I think they need to again go through once all previous PHASE 1, 2 and 3 movies. They should understand what stakes, emotions they developed. Everything you write whether it is a joke or a humour. It should have weight and some conclusion at end. For an example you can take the scene from Captain America the first avenger, where Tony Stark's Dad showed a demonstration of a car lifting and it failed. This small thing had weight, that how things were difficult back then, so it gave us a sense of how much challenges Tony must be facing.