Begin a story with a given first line. Here are some to choose from:
- Where were you last night
- The neighbors were at it again
- I met him/her on the stairs (note how many different ways the characters could be moving: both up, both down, passing eachother.)
- "One more thing before you go"
- This is a story I've been avoiding for a long time:
- If I went there a second time...
- I haven't been the same since...
- See that house over there? Let me tell you...
The idea is to start the story in the middle of things (in media res). These lines work well because they start after something important has already happened and can be a dialogue or narrative.
(Summarized from 'What If? Writing Exercises for Fiction Writers' by Bernays & Painter; Pgs. 21-22)