To me, it’s harder to write a good short story than a novel. If you’re a good / great editor you have a better chance.
Typically I don’t try to tell the entire story. The first one I ever got published was a silly little romance that focused on the proposal. There was no lead up about how they met, and no conclusion about the ceremony. I just wanted to tell a “slice of life” tale about two very nervous people. It ended up being six pages long and it won me a computer. 😉
Think of something interesting. One single thing. Another story of mine was about a mother and daughter in a park. The mother was depressed, you never find out why. The little girl picked a dandelion but when she asked what it was, she misheard. She thought it was a “Daddy Lion”. So she wandered off, then returned with another. She put it in her mom’s hand and said “That one’s a Mommy Lion.” The mother saw what a little miracle her kid was, end of story.
Try to capture one emotion, one idea, one image. If you can do that you can write a great short story. 🙂