(A response to the prompt “What’s your favorite way to start writing?” when you don’t know what the story is yet.)
Although it doesn’t often work out this way, the most enjoyable part of my writing process happens when I’m scribbling longhand in a notebook somewhere pretty outdoors, about whatever I find interesting or silly or disconcerting at that moment, until … an idea forms. Excited by the possibilities, I continue scribbling until a story begins to evolve. Eventually, witnesses will report a crazy person running home to the computer to see where the ideas take her.
For me, paper is slow and good for thinking;
The keyboard is fast and good for writing.
You might want to try this yourself if your ideas have difficulties gestating. Perhaps it will work for you, too. Tell the police I put you up to it.