Two USC students recorded this video of interviewing tips in 2011.
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: