You are in the Emotion Pictures business. So, when writing a scene, ask, “How are these people feeling?” All these people. What are they feeling now?
At the beginning… what was he doing before he walked into this elegant bar? What had happened and how did it make him feel? How is he showing us what he’s feeling? In the middle of the scene, stuff is happening. How is it affecting him? Is it changing his (or her) mood? And, at the end, how does he feel NOW? Where will he go next? Infused with this new feeling / mood that the scene fostered in him, what will he do?
When I say, “Go around the room,” I mean check in with every character, not just the ones with dialogue. Take everyone’s pulse at various points during the scene. Not just the principals. If we need to know how they feel, show us. Please don’t tell us about every single character all the time, but look around the room and, if someone’s doing or feeling something useful, communicate it. It will be interesting to see what fresh, strong, wonderful moments you find.
A superb reason to add reaction shots to your script is, when you make the movie, they will help your editor. Often, laughs happen on reaction shots, not on the person speaking. If you don’t have the coverage, your editor can’t get the laugh. For all kinds of important reasons, your editor will want to cut away from the primary players in a conversation. But, if a reaction shot is not on your shot list, you’re not going to shoot it.
When your editor says, “Have you got a single of Matilda?”, she needs that shot. If you don’t have it, she’ll smile, think you’re an idiot, and keep working. Reaction shots start with the screenplay. If you don’t go around the room while you’re writing, you won’t have reaction shots when you get to the editing room.
I can’t overstress the need for reaction shots. Put them in your script. They perk up the read and will give your editor the coverage she’ll need to save your ass.