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.
Neil GaimanEverybody who has ever read Sandman knows exactly what the Sandman looks like, which is more than anybody who has ever read The Catcher in the Rye can say about Holden Caufield.
Neil GaimanWhat should I believe? thought Shadow, and the voice came back to him from somewhere deep beneath the world, in a bass rumble: Believe everything.
Neil Gaiman