1) The story begins to flow once you pinpoint the right idea

The book is the idea. Once you have that idea, it just flows out. This is perhaps the best advice I can offer. Taking an idea, a central point, and pursuing it, turning it into a story that tells something about the way we live today. …Telling a good story demands a great conception, a great idea for why the story works — for what it is and how it connects to the human condition.  It is about ideas, about narration, about telling a story. You must be able to point to something larger.”
–David Halberstam, in Telling True Stories (2007)

2) Most stories worth telling have a personal connection

There are zillions of ideas out there—they stream by like neutrons. What makes somebody pluck forth one thing—a thing you’re going to be spending as much as three years with? If I went down a list of all the pieces I ever had in The New Yorker, upward of ninety percent would relate to things I did when I was a kid. I’ve written about three sports—I played all of them in high school. I’ve written a great deal about the environment, about the outdoors­—that’s from thirteen years at Keewaydin, in Vermont, where I went to camp every summer, first as a camper and then as a counselor. I’d go on canoe trips, backpacking trips, out in the woods all summer, sleeping on the ground.
–John McPhee, Paris Review interview (Spring 2010)

3) Become aware of your obsessions, and write accordingly

Some will tell you that in order to write you should nurture your obsessions, but this seems a bit of a tautology—aren’t obsessions, by their nature, already being watered, daily? Maybe it is more important to simply become aware of your obsessions—none of mine have ever gone away once I name them, besides, the act of naming is as much a Rorschach as anything else. Naming will at least allow you to be dimly aware when you once again wander into that realm—be it the mom realm or the dad realm or the sex realm or the money realm or death realm or the time realm—whatever your obsession it will be clear that you are there again.
–Nick Flynn, Bennington College commencement speech, June 19, 2010

4) News stories are often endings without beginnings attached

One of the best ways to find [story ideas] is to read local newspapers, the smaller the better. Resolutions, because they so often involve an accomplishment or highlight change, lend themselves to the quick and dirty, one- or five-inch stories that can be printed around tire ads. Local police crack a stolen-home-computer ring. A politician gets elected. A handicapped person forces the city to install a ramp into city hall. Someone gets a prize, receives an award, is honored at a banquet, gets a promotion, earns a degree, paints a mural, or otherwise makes a mark on the world. Those are all resolutions to some unknown complication or complications, and the newspaper serves them up to you for almost nothing. From the dramatic point of view, of course, the local reporter misses the point when, in typical news fashion, he concentrates on the culminating event — the awarding of a certificate or the arrest of a petty crook — while ignoring the actions that led up to that event. Most news stories are endings without beginnings attached.
–Jon Franklin, Writing for Story (1986)

5) If in doubt, focus on characters and motivation

After we talk about what a play is, I ask them to invent a painting in their minds and then describe it in words. …If you tell them to write a description, they get too conscious and can’t do it. Let me give you an example—in his word-painting a guy will describe a train station. He says, “There’s a woman wearing a white dress over there and some guys sitting in another part of the station.” Then I start asking questions. “Is she coming or is she going?” “Going.” “Where is she going?” “To visit her grandmother.” And simply by asking these questions we find out who this person is. Then we’ll find out about these guys over in the other part of the station. All of a sudden the student yells, “I can write a play about this!” You’ve caught him by surprise. Until he began fleshing out the painting, he didn’t even know who the woman was.
–August Wilson, Paris Review interview (Winter 1999)