There are times when it may be good to have someone else’s perspective on some of your material. One reason to interview others is to get their impressions of the time when you were a small child or before you were born. You might choose to interview an elderly relative to see how they remember things.
In conducting interviews with others it’s probably a good idea to have a tape recorder unless you are an experienced note-taker and interviewer. You should ask permission to use the material. Most people will be flattered and say yes without any problem but sometimes they will ask that you show them the material as incorporated into your manuscript before you share it with anyone else. They may want to make sure you have accurately represented what they told you. Don’t take offense; simply accede to their request.
If this is an important source and you think your subject will have quite a lot of material that you can use, invite your subject to record a few sessions. You don’t have to be there. Simply give your subject some questions to answer and leave the tape recorder.
If you are present, don’t keep interrupting with your own thoughts. This is your subject’s time to speak. If something isn’t clear ask for clarification, but otherwise let your subject talk until they run out of steam. Then ask a question to see if they have more to give you.
When you are ready to incorporate the material, you can quote your subject directly, with attribution, or paraphrase their words with a short introduction, such as “When I spoke to Aunt Milly about this, she said ….” Make sure you give your subject credit for the material. Don’t try to pass off the material as your own. That might make you an enemy.