Take a book off the shelf and write down the opening line. Then substitute as many words as possible with your own words, keeping the syntax and parts of speech intact. Then keep writing. Performing this kind of literary "Mad Lib" often creates a useful starting place for a story, especially when the sentence contains an intersection of character, setting, and situation. Or try using these opening lines, from Faulkner, García Márquez, and Plath, respectively:
Through the [concrete noun], between the [adjective] [concrete noun], I could see them [verb ending in "ing"].
It was inevitable: the scent of [adjective] [plural noun] always reminded him of the [noun] of [adjective] [noun].
It was a [adjective], [adjective] [season], the [same season] they [transitive verb, past tense] the [family name, plural], and I didn't know what I was doing in [city].
This week's fiction prompt comes from fiction writer Eleanor Henderson, whose first novel, Ten Thousand Saints, will be published by Ecco in June.