Tough question. Sometimes the answer is, "things just come to you," although many times, my answer would be: prayer, grit, work, and agony. I'm only slightly exaggerating.
Occasionally, I'll be inspired by things I find in my genealogy projects, stories I read, or historical happenings.
For instance, I'll see something in an old newspaper that makes me say, hmm.
I was perusing a paper from 1909 and this story caught my eye:
Rancher SuicidesEly, NV -- "...a rich sheep rancher ... committed suicide in a saloon in this city today by taking strychnine. His mind was temporarily deranged."
What? When I read he'd committed suicide in a saloon, I thought there would be a gun involved. But strychnine? Why did he bring a poison with him to a saloon? Why did he want that particular audience? How did the observers know he'd brought strychnine? Did he make a show of it, or quietly slump in the corner?
There has to be more of a story. Who was he really? Why did he do it? Why, why, why?
These mysteries are often the seeds of a story.
How about you? Where does your imagination take you when you read the news clipping?