Every story would be another story, and unrecognizable if it took up its characters and plot and happened somewhere else ... Fiction depends for its life on place. Place is the crossroads of circumstance, the proving ground of, What happened? Who's here? Who's coming?
The first act of insight is throw away the labels. In fiction, while we do not necessarily write about ourselves, we write out of ourselves, using ourselves; what we learn from, what we are sensitive to, what we feel strongly about--these become our characters and go to make our plots. Characters in fiction are conceived from within, and they have, accordingly, their own interior life; they are individuals every time.
What I do in the writing of any character is to try to enter into the mind, heart and skin of a human being who is not myself. It is the act of a writer's imagination that I set the most high.
Characters take on life sometimes by luck, but I suspect it is when you can write more entirely out of yourself, inside the skin, heart, mind, and soul of a person who is not yourself, that a character becomes in his own right another human being on the page.
Once you're into a story everything seems to apply-what you overhear on a city bus is exactly what your character would say on the page you're writing. Wherever you go, you meet part of your story.
Dialogue has to show not only something about the speaker that is its own revelation, but also maybe something about the speaker that he doesn't know but the other character does know.
A short story is confined to one mood, to which everything in the story pertains. Characters, setting, time, events, are all subject to the mood. And you can try more ephemeral, more fleeting things in a story - you can work more by suggestion - than in a novel. Less is resolved, more is suggested, perhaps.