Short story writing is fun but not easy. Here are some rules to follow:-
Do your market research. Read as much media as possible of the genre you will be writing. See what types of characters and story lines work best. If you are wanting to write for a magazine check the word limit carefully. Their rules are strict and any story outside the limit will be rejected.
Consider the plot carefully. It is central to a short story.
Include plenty of conflict to test the main character. There should be lots of tension situations and climaxes.
Keep the dialogue simple.
Develop your characters by ‘showing’ not ‘telling’ what they are like; In other words, by what they say and do.
Don’t ramble. You have a very restricted word limit.
These and other rules are developed in my article at http://www.infobarrel.com/Write_A_Short_Story
You might like to drop in on my Infobarrel site and read some of my other 50 articles.