I once wrote a short story about a girl who was possibly (or possibly not) possessed by a demon. In this story, I went on and on for about 48 pages. Yes, I said a short story. Throughout the story, I threw in every bit of information about exorcism and demon possession that I had gathered in the course of my research, as well as every possible variation of scene that I could think of.
I thought of this as thoroughness, but then, after I’d set it aside, I had to ask myself if all of that verisimilitude had really been necessary to tell the story. I ended up going back and cutting fourteen pages out of it.
Some of those fourteen pages were really dear to me. You know how it is—clever turns of phrase, good observations, scary setups. But none of it added any significant momentum to the story.
Which brings me to my point. Your maxim when self-editing should be, “Is this scene (sentence, description, and so forth) really necessary to tell my story?” Sometimes, you may think so, but you’re not sure.
What do you do then? You experimentally delete it. If the story arc flows on just fine without it, then it was just distracting filler.
Deleting such material is often painful to do—especially if you’re writing from personal experience. Or you may be writing a tale with a message that you think the world needs to hear, and you may find that some of what you were certain you had to say just isn’t important to the story. That’s the hard stuff to cut, but this is no time to get on a high horse.
The moral is, if it’s bad, kill it. Verisimilitude is always necessary in order to create believable fiction, but when all that detail becomes mere decoration around the action, either it has to go, or your readers will.