Far too many people write lifeless scenes. A typical screenplay consists of 90% expository scenes that do nothing but explain the story, and 10% exciting scenes that incorporate all the exposition introduced by the bulk of the screenplay. This is a formula for failure.
What you need to do is make every scene like a mini-story that’s compelling and exciting in its own way. That way readers will be pulled along from start to finish and the entire screenplay becomes interesting. One way to do this is to make sure that in every scene, the other characters are either helping or hindering your hero.
What you don’t want are characters who do neither because they’re pointless. Even minor characters need to hinder your hero. In the bar scene in “Star Wars,” there are numerous characters who never interact with Luke at all. Yet their very presence intimidates Luke so this collection of motley characters work against Luke.
Later in that same scene, two rough characters start harassing Luke until Obi-wan saves him by killing both characters. Once again, these two minor characters are working against Luke.
Even in the earlier scene in “Star Wars” where Luke is talking to his aunt and uncle, the uncle is blocking Luke’s wish to get away while the aunt sympathizes with Luke. All characters must either help or hinder the hero or else they have no purpose in the scene.
In “Titanic,” Rose first boards the Titanic with her mother, but already her mother is pressuring her to accept marriage to a man she doesn’t love. It’s easy to have bad characters opposing your hero but it’s often far more interesting to have seemingly good characters opposing your hero. In “Titanic,” you would think the mother should help Rose, but in a twisted way, the mother is actually working against Rose in much the same way that the uncle works against Luke in “Star Wars.”
Pick any scene in a good movie and you’ll see that the other characters either help or hinder the hero. In “Little Miss Sunshine,” the entire family drives off to bring Olive to a beauty pageant. Along the way, they fight each other so they hinder each other. Then later they support each other, which shows their emotional change but also creates a far more interesting story than completely bad characters who do nothing but do evil all the time.
When writing a scene, always think of every character either hindering (most of the time) or helping your hero. That will help create conflict and make a scene more interesting than just characters doing nothing at all.