A common mistake in writing dialogue is to include conversation that does nothing to move the story forward. Example:
“Hi,” I said. “How are you?”
“Okay thanks, and you?”
“Couldn’t be better. Looking forward to the weekend.”
“It’s been a long week.”
… and on and on.
A short meaningless phrase may be okay to get the action going, but your second character better have something meaningful to say pretty soon or the reader will disengage. That answer to “How are you?” needs to have a punch or just ignore the question. Or tell us why the week seemed so long and don’t delay about it.
Here’s a short example from “Winter is Past.” Mundane conversation, but it carries the story another step forward.
Kathryn sat on the edge of the bed and sipped apple juice from a cardboard container. The curtains were drawn, blocking the light. “What time is it?” she asked.
“Just after one. You okay?”
“I’ve got to be. I plan to go to work tomorrow. There’s only a few days to get things squared away. Brian scheduled the surgery for next Monday.”
Review one of your own short stories and try to identify snippets of conversation that go nowhere. Eliminate them entirely or add something that gives the reader a reason to be involved…something that moves the plot along, expresses emotion or mood, establishes a sense of place. Anything that gives it a raison d’etre.