Before delivering an important speech, people rehearse. Before performing before a large audience, people rehearse. When you rehearse, you build up your skills and you improve what needs improvement. When you practice excellently, those experiences are stored in your brain cells and you can access them again and again.
Before a potentially difficult encounter with someone, mentally rehearse. In your mind's eye imagine yourself getting along smoothly. See yourself remaining calm and friendly the entire time. See yourself speaking with respect and kindness to the other person. Imagine that this person will speak to you in a friendly way.
This mental exercise is a powerful tool. It works either positively or negatively. If you imagine that someone will speak and act negatively towards you, this imaging will put you in an unresourceful state, and will make it more likely that you will help create that negative reality. With equal effort you can choose to utilize it positively.
(from Rabbi Zelig Pliskin's book: Harmony with Others, p.77, www.artscroll.com)