I recently received this useful piece of advice from Larry Niven via a quote in an email:
If you want to know that the story you’re working on is saleable, try this: I tell it at a cocktail party. I dreamed up “The Flight of the Horse” one morning, outlined it that afternoon, and by that night was telling the tale to a clutch of cousins. I held their attention. I didn’t miss any points. I kept them laughing. The noise level didn’t drown out anything subtle and crucial. Then, of course, I knew how to write it down so I could mail it and sell it.
I told the sequel the same way (“Leviathan!”) and sold it to Playboy for what was then fantastic money.
This makes for good memories. It’s also a useful technique.
Some of the best stories simply can’t be told this way, and I can’t help you write those. Nobody can. They are rule-breakers. Try some early Alfred Bester collections. But any story you can tell as a cocktail/dinner conversation, without getting confused and without losing your audience to distractions, is a successful story.
If you’re like me and you don’t typically get into social situations where throwing out your latest story would be welcome, I’ve found walking through it aloud on my own can be helpful. I have even recorded my “pitch sessions.” EXTRA TIP: If you run through your pitch aloud in the car, stop talking to yourself at the stoplight, especially if you live in a state where cellphone use in cars is illegal and, like me, you work in the same building as the state police headquarters.