In one page, say everything important there is to say about the world. (If you had only one page to fill with everything vital, urgent and necessary that you know/feel/suspect, what would that page be? Of the world as you have experienced it, what is absolutely crucial to report?)
Write a story containing no living things.
Do a false expert piece, in which your narrator holds forth, incorrectly but with authority, on a subject of which you have little information.
Write a story with no use of metaphor, simile, or comparison. Attach no value or interpretation to any of your statements. Determine if there is a way to create meaning without naming it.
Describe a photograph (a frozen instant of time) and attempt to give it movement and tension. Don’t mention that it is a photograph, simply treat the photo as if it’s the fictional world you’re developing. Most importantly, don’t allow things to advance in time. Keep to a single moment.
Write 15 first sentences for potentially great stories.
Write a first person story from the perspective of someone entirely opposite from you. The idea here is to get out of yourself and empathise with a character foreign to you.
Write a story in a genre that you know nothing about, or that you don’t much like (mystery, romance, sci-fi, etc.)
Inhabit the perspective of someone that you despise, and try to write a convincing fiction.
Write a short story that covers a great deal of time (many years in the life of one person, or hundreds of years in the life of a town, etc.).
Tell one story from several different points of view. Every perspective of the same event has its own dramatic and narrative possibilities. Make a fiction that explores these possibilities.