The best advice I can give on this is, once it's done, to...

The best advice I can give on this is, once it's done, to put it away until you can read it with new eyes. Finish the short story, print it out, then put it in a drawer and write other things. When you're ready, pick it up and read it, as if you've never read it before. If there are things you aren't satisfied with as a reader, go in and fix them as a writer: that's revision.