How would you start a story?
The most important considerations would be in creating a viewpoint character and giving that character a motivation that would carry him or her throughout the story. The story should be about somebody who wants something and has to overcome some obstacles in order to obtain it. Of course, the protagonist may fail to obtain it in the end (as for example in Jack London's "To Build a Fire."). We identify with a character on the basis of what he or she wants--so what he or she wants (the MacGuffin) should be something that most people could imagine wanting themselves (e.g., love, money, fame, survival, revenge). The next most important consideration would be what Edgar Allan Poe called "the effect." What is the emotional effect you wish to obtain? A wise teacher once told me that the best way to write a story is to look for a "turning point" in your own life--that is, something that happened to you that was so thrilling or so traumatic that it made you a different person. I hope these hints are helpful.