You must reveal who they are and what they want, their hopes, dreams, and fears, by how they say it as much as what they say. Good dialogue tells us more about what’s going on in its subtext than on its surface. Subtle is better. And talking the plot is like using a sledgehammer. It’s overkill. An adjunct to this rule of bad dialogue is “Show, Don’t Tell”. Movies are stories told in pictures. So why would you resort to telling us when you can show us?

By showing and not telling, you leave room for your characters to be at their best — that’s being active, with their own separate agendas for being there, not yours. The truth is that movies are so much about what happens that we must learn about characters by what they do, not by what they say. As in Life, character is revealed by action taken, not by words spoken.