You can write down the answers to the questions, or do an audio or video recording. Recording the interview ensures that you don't miss anything and also allows you to review the interview at a later time.
If someone is talking about an unhappy or painful experience, show that you understand how they feel ("That's very sad"). If the person doesn't want to talk about something, that's okay – just go to the next question.
Free 65 - Year Old Person Interview Essay Sample
An interview shouldn't last more than about an hour. People do best when they're not tired. You can always do another interview. Doing several interviews actually allows you to think about answers, and come up with other questions based on the answers and things that interest you.