Two USC students recorded this video of interviewing tips in 2011.
If you have identified an expert with insight into your topic, but you cannot find their own statements or a published interview with them, you can try contacting them directly. This could take the form of a written email exchange, or an interactive conversation or interview over the phone, in person, or by web conference.
Thomas Mann devotes a chapter to interviewing sources in his book The Oxford Guide to Library Research. He says that journalists are used to using interviews to get information, but this strategy can work for any researcher when the situation calls for it.
Mann has several recommendations for how to gather information by talking with people:
For background research on a person or place, check for news articles written by journalists.
If you're researching a person, look up their own statements on a professional or personal website, on social media, or in published interviews.
If you're researching a place, first identify the aspects of that place that interest you. News articles or local government websites may be useful starting points. As you identify other concepts related to that place, try searching for books and articles on those concepts.
Here are a couple of library databases that could be helpful:
Here are some resources on interviewing and using people as sources during the research process: