Common user-story mistakes leave the project team out of writing, name an undefined who, make the why feature-specific, leave acceptance criteria vague, or assign the story to implementation without discussion. Those errors hide whose motivations matter or remove a true-or-false test of done, so the story often needs extensive rewrites or does not produce the intended result. Stories can be refined many times, but shortcuts should not be taken: involve the team, use defined personas, keep user needs first, and review intention before development.