Curious things, habits. People themselves never knew they had them. [Witness for the Prosecution, also published in The Hound of Death and Other Stories.]
I try to turn a written thing, when I'm in trouble with it, into a spoken thing: I start imagining what I would say to someone if I were trying to tell the story or make the argument.
I set myself up for a lot of trouble by wanting to tell a story that is fairly earnest and emotional and expressive, but to do it in the most subtle, realistic way.