I treat every scene like an action scene. I don’t mean that I have people doing Kung Fu while talking, but I try to make every scene full of the tension and kinetic feel that someone gets from an action scene. There’s a give and take of the characters. They are doing things when they react that show their emotions. I think of what the reader is feeling when reading that scene and how I want them to get the rhythms. It’s a very film-centric way to do things, but that’s where I came from!
I also treat every time a character opens his mouth as important. Not sacred (because I’m not pretentious), but a chance to learn more about them. A phrase they use tells us where they’ve been and makes the reader build a backstory in their minds that holds their interest.
Take this line from The Empire Strikes Back: “No disintegrations, this time,” said Darth Vader to Boba Fett. That little exchange makes the viewer wonder about their backstory and build that in their mind. What happened last time? How long have they been working together? Do they trust one another? The operative phrase there was "this time." Get rid of those two words, and the exchange isn’t memorable because nothing is built within the viewer's imagination. So yeah, I try to do a lot of that.
I’m a believer that it’s hard to learn how to write dialogue, maybe impossible. Probably because I never had to learn it. I just listen to the voices of my characters in my head. You have to be able to hear those voices. If you can’t, it’s hard to fake it.
Finally—I try to put the reader into the scene. What’s a plasma blast smell like whizzing past your head? What does it feel like when there are a thousand giant alien spiders bearing down on you? I try to give the visceral sense of things like that, but you can only do that a little bit, or else the scene gets bogged down by environmental details. Throw in one or two and let the reader fill in the rest.