STAR structures your behavioral answers: Situation (set the context in sentences), Task (your specific responsibility), Action (what YOU did, not the team), Result (quantified outcome).
Use "I" throughout, not "we." Your interviewers want to know YOUR contribution. Bad answer: "We launched the feature." Good answer: "I designed the API, coordinated with teams, and we shipped weeks early."
Keep answers under minutes. Practice out loud until the structure feels natural.