1. By showing confidence on face and body posture that you know all dynamics of the position applied for.
2. Show your attitude and seriousness towards job by giving to the point answers.
3. Try to ask relevant questions to have complete mental clarity about job description.
4. Try to show that you are needy of job.
They are asking for you to remember and describe three situations at previous jobs that serve to demonstrate the qualities you want to exhibit, and in the telling, you should highlight which trait you are showing. "I remember that my boss said xxxx and I responded with this xxxx action, and to me that shows my ability to be xxxx". Like that. It could be any three situations you recall and describe and three attributes you want to show. It can be relating to situations you had with your boss, your boss' boss, your co-workers, customers, clients, and even your boss' secretary. Anyone, any situation, at work, and the attribute you think it shows.