In a 350 words short story, one common element is a concise beginning that sets the stage. It quickly introduces the situation or the characters. Emotion is also important. The story should evoke some feeling in the reader, whether it's joy, sadness or surprise. Additionally, a good short story of this length often has a unique voice or perspective that makes it stand out.
Common elements include a clear setting. It might be just a brief description but it helps the reader visualize the story. Another is conflict. There has to be some sort of problem or struggle, whether it's internal or external. And finally, a resolution. It doesn't have to be elaborate but should give a sense of closure within the 350 words.
A strong plot is common. Even in 350 words, there should be a clear sequence of events. Also, relatable characters. They don't have to be complex but should be believable. And a theme, like love or hope, that ties the story together.