The way I look at it, a scene should ideally have at least three actors in it, most commonly two characters and the scene’s setting. But it’s not enough to simply make your characters look around the room, or having random stuff happen here and there.
That, in and of itself, isn’t interesting. You could have your characters chatting in the middle of a war zone; that setting isn’t going to make things interesting if all it does is make your characters speak louder, or move a couple of feet every once in a while to avoid a mortar shell. If the war doesn’t impact them directly, then who cares that they’re in a battlefield? Why are they even there?
In order for your setting to be an actor in your scene, it needs to become a character.
Imagine you’re writing a love story. Husband and wife are sitting on a bench at the park, talking about having a baby. The husband is still scarred by the death of his first wife and baby in childbirth.
So far pretty dull, right? Okay, so you could apply the usual advice: throw in some arguments, some conflict, some shouting… But all that’s going to do is artificially delay a result we already know (he’s going to accept, because that’s the only way the story progresses), or lead to a result that produces no forward motion (he stands his ground, thus causing the entire scene to be pointless). Still pretty dull either way.
What about if there’s a pickup basketball game going on next to them? A stray ball rolls over to the husband. He picks it up, and just touching that ball reminds him of the joy of expecting the birth of his first child. Now you’ve got the setting speaking to one of your characters.
Cliché? Perhaps. What about if you told the scene from the point of view of the wife? She sees her husband change his mind out of nowhere after picking up the ball and staring at it blankly for a few minutes. She doesn’t understand why. Maybe the wife doesn’t know her husband as much as she thought she did. Now we get an excuse for delving into his state of mind.
Think of it as an invisible third character whispering something into the first character’s ear. And here’s the cool thing: in so doing, that invisible third character also speaks to the second character, albeit whispering something else.
Anyway, I’m sure you can come up with something more elaborate as it pertains to your story. That was just an example to give you an idea. But just think of the possibilities if you can turn something boring like chatting on a bench into something interesting.
The key here is subtext. It is subtext, and more generally nuance, that will make your dialogue come to life. This includes double-entendre, misdirection, foreshadowing, things thought but left unsaid, modulation (commentary interspersed with the dialogue that adds layers of meaning to your characters’ interactions), etc.
I’ve read books with giant walls of dialogue that didn’t particularly bother me and that have, in fact, been very successful. People don’t care that something is long if it’s interesting. Make your dialogue interesting and you’ve solved your problem.
KM Weiland of Helping Writers Become Authors also cites the following example from The Ten Commandments:
There’s an early scene in which the jealous crown prince Ramses is
dropping weights into a scale to emphasize each of his accusations
By the time his accusations are finished, the scale has enough weight
on one side to clunk all the way down against the table.
Moses then rebuts the accusations by picking up a brick, saying
starving slaves can make no bricks, and then thunking the much heavier
brick down on the other side of the scale.