There are many ways to approach interviews and every solution depends on context- form follows function; but from my experience in non-fiction video, I have found it useful to make these things habitual:
1. Think strategically
Know what kind of contribution you want from a given subject so that your time with them will be purposeful. Before you ask the questions, before you write the questions, before you even book the interview! Know what you need from this person, whether it is general or specific.
2. Crew up
Whether you bring a professional videographer, gaffer and sound operator, or you are a one-man band, make sure you know how to get good video and audio. Having the bases covered technically will ensure solid footage and when done right, allow you to focus on the big picture- your subject & the content.
3. Do your homework
Research your subject, including their work and their milieu. For the video pieces I make, I often interview experts on specific fields or industries, people who are very accomplished at what they do. They are often media savvy and can detect an insincere journalist or TV producer a mile away. Even experts will forgive a cursory understanding as long as you demonstrate sincere interest, so a little research beforehand can go a long way towards getting a more engaging interview “performance”. Which leads into my next point:
4. Direct your actors
In a documentary or non-fiction piece, interview subjects are your actors. Some are more natural and experienced at it than others, but always remember that your subjects are your performers and just like on a movie set, you as the director have to create the conditions for them to make a compelling and unique contribution. By agreeing to be interviewed in your video, people are trusting that you know what you want from them, know how to get it, and will present them well. Don’t let them down!
5. Get b-roll
Illustrate your subject in their environment, especially if the interview is something very typical like a non-descript background or limbo space. Whether it is a tv segment, a documentary, a marketing video, it can be very useful to have footage of your interviewee in their laboratory, at their workstation, polishing their motorcycle, teaching, playing the violin, anything that shows them doing what they do. You may need b-roll to cover an edit or simply introduce your subject, or may not use it at all- but you are already there and tape is cheap. It is so easy to get these shots while you have the opportunity that there is little excuse not to.