Your story must always be moving forward. Even when you use flashbacks, they must help to move your story forward. It’s a point that is difficult for people to understand. When I am editing a piece of fiction, I am always looking for stray thoughts that will disrupt the flow of the piece and draw the reader out of the action.
You know you have succeeded if your reader becomes totally immersed in your story. They become a character standing at the side of the room hearing, seeing, smelling, and feeling everything that is happening to the other writers. When writing, don’t insert anything that will upset this participation on the part of your writer. If you do, delete it.
That’s a simple tip, but one hard to implement. Try it.