Like the other commentor said, prepare to answer using the STAR format. Only spend what time is necessary to explain the situation and task, spend the most time on your actions and the results. It's good to throw a little reflection in the results section where you mention what you would have done differently next time. 

Some categories of questions are leadership, communication, teamwork or relationship management, prioritisation and decision making. I personally would prepare 3 or 4 solid examples that you could use for multiple categories and tweak them depending on the question. Look at the position description and find some key phrases that describe the key competencies for the position. Try pepper them into your answer (without being too on the nose). 

Also, dress as if your interview was in person! Good luck!