All too often, it’s easy to write a short story that you absolutely love–only no one wants to buy it because it doesn’t fit within the confines of their publication. One trick you can use to get around piling up flash fiction pieces that are hard to market is to pick a few markets that you want to target and get a grasp of their publishing style, even before you put any words on the page.
Another trick is to read short story authors in a similar vein and pay attention to where they are getting published; this usually requires you to be brutally honest and objective about your own work and its quality. Once you get used to “marketing” your unwritten story ideas, you’ll be able to make better decisions intuitively to write a short story or flash fiction piece that you can sell.