If you tape record it, label the tape with the date and the name of the person. Even if you tape the interview, you should take notes so that you'll remember important points. At the beginning of the interview, ask when and where the person was born. This will save you from having to backtrack and figure out dates later. Don't interrupt or correct the person you are talking to.
People sometimes remember things wrong.
That's okay-you can check dates and facts later. The important thing is to hear about the person's impressions and feelings. Something the person says may inspire you to ask a question you hadn't planned. For example, let's say that the person you are talking to mentions that she will never forget seeing television footage of the Kennedy children at the president's funeral. You might ask why it was so unforgettable.