If you want your writing to be taken seriously it is very important that you take the initiative to rectify the common mistakes. Here’s an article listing the most common mistakes made by story-writer. However, it covers only the most common one. There are several other mistakes you might want to avoid.
Short stories are called short stories for a reason. So don’t go on adding details and making it too long! If too many sub-plots, too much information, too many characters find their way into the story, the length moves from short story to novella or novel.
Be catchy! Short stories have very little time to hook the reader to them. So your writing has to be such that it attracts the reader’s attention within the first three or four paragraphs.
Also short stories require originality. Do not try to take up the same old boring ideas used by almost all writers. Be innovative, let your imagination fly and write something different!
Now when I say let your imagination fly, I don’t mean that you don’t get your facts straight! You must research and make sure that you write correct information!
Also, there shouldn’t be lots of confusion. Having the mechanics correct is a must. Mixing format, construction, thesis, structure, or points of view results in the reader being confused. Also not following the guidelines for the genre can result in readers who expect certain elements that are missing or misused.