Howdy,
As June come to an end, I excitedly anticipate my two short stories coming out in July. It reminds me of some advice I heard from John Scalzi, award-winning sci-fi author extraordinaire, a couple of years ago at a local library. He was doing a promotional tour; I don’t remember for which book. As I recall, most people, like me, knew him from his breakout novel, Old Man’s War.
The advice he gave, and I’m paraphrasing this since my memory is admittedly hazy, is to write short stories and to treat them as writing assignments. For example, Scalzi claimed to have had difficulty creating nasty, despicable characters, so he wrote a story with a protagonist possessing those traits. By treating the story as a writing assignment, he wasn’t concerned if the work ever saw the light of day and if it ever did, that was just gravy.
I think I've put this advice to great use. Since that day, I’ve written a dozen or so short stories and had most of them published by different outlets. Each one I’ve treated as an assignment, focusing on a different aspect of writing (usually characterization). If nothing else, my writing has improved far faster than I ever imagined possible.