Many writers, especially new writers, have trouble with scenes. They can picture the beginning of their story and the end, but what comes between gets a little hazy.
The key to keeping your story moving is to be able to write a good scene, and to keep those scenes coming. And the key to a good scene is conflict.
Pages of prose do not a scene make, nor does dialogue between characters. Unless there is some sort of conflict and movement from one value state to another, you don’t have a scene. You should have movement from negative to positive, or vice versa. Hate turns to love, or guilt to innocence. Each scene should have some sort of “turn” or movement.
Make sure your scenes go somewhere. They must follow the story pyramid: inciting incidents, progressive complications and tension, climax and resolution. If you get stuck, think about your character arc: is your character getting closer to his goals or further away? It has to move in one direction or the other along the arc for it to be a successful scene.
Unfortunately, the easy to understand scenes are often the most difficult to craft. The scenes that stick in a reader’s mind are the ones you’ve had to edit and re-edit to perfection. And when you’re writing scenes, remember: the first thing that comes into your mind is something that’s already been done. Go deeper and seek out the real tension and conflict that will drive a truly memorable scene.