The most important rule to submitting a short story for publication is to watch the guidelines for whatever media the piece is being submitted to, according to Writer's Digest. Being well read in the media a piece is being submitted to is also important, as is including a cover letter with the piece explaining what the general idea is and why it should be considered for publication.
It is important to watch guidelines to improve the chance of being published, states Writer's Digest. Sending in a romance piece set in a historical time period to a magazine specifically for futuristic science fiction will ensure a flat out rejection that will now be associated with the piece of work. Being well read on the media is important for reasons along the same lines.
Reading works in the genre a piece is being considered for will help the writer figure out the general tone she should be going for. A science fiction magazine piece geared toward teenagers will need to be different than a piece that is being submitted to a magazine for adults.
Including a cover letter allows an editor to get to know the general feel for a piece, and can ultimately be what either gets attention or causes the story to be rejected. A cover letter also looks professional and is a common courtesy in the world of writing, according to Underdown.