Here is a link to a really good article with interview tips.
Sr. Editor/Director of Post Production Operations
Moving Pictures, Inc.
Things I tell my subjects:
TV is not a "mass medium". You are not talking to thousands of people at once. Rather, you are talking to one person at a time, many times over. Just work on talking to that one person. Make that person... me.
I' getting paid to make you look good, not bad. I'm going to throw out the bad takes and only save the best parts.
You can control this: if you didn't like what you said, we can start over and you can tell it again until you're happy.
Things I don't tell my subject:
That I've turned off the red tally light and while they think we're just chatting about nothing, while the sound and light guys are fooling around with final settings, we're actually rolling.
When I say we're done, we're still actually rolling.
I don't stop rolling until you get out of the chair, and I've been rolling, with tested levels and lighting, since before you sat down.
Other things I do:
Always ask open-ended questions, don't ask questions that have yes/no answers. Try to get them to incorporate the question into the answer, and demonstrate this by having them ask YOU some questions. The sample I usually give is this one:
"Ask me what my favorite ice cream is"
"What's your favorite ice cream?"
"My favorite ice cream is Rocky road, because it has nuts, marshmallow, chocolate... so many different textures and flavors in one thing, and it's that mixture that appeals to me..." Ask them WHY questions, HOW questions. Ask them to "tell me the story about".
Ask the same questions more than once, and not necessarily in the same order. Re-phrase them. Be on a different angle for the second try. Always re-ask the first question as your last question; by then, the subject is really warmed up and will give a better, tighter answer.
I make it a point to turn off the servo zoom so I can change camera angles VERY FAST manually, with just a flick of the wrist, while I'm asking the question, so they are already re-framed, tighter or wider, when they are ready to respond. If you do nothing else to help the edit process, do that one thing during the shoot, because 90 minutes of one locked-off angle is MURDER for editing.
I didn't read the linked article yet... but in a previous life a few moons ago I spent quite a few years as a television news reporter, and found that interviewing people is quite easy if you do it right... but if you do it wrong, it can be murderous.
As Mark said, I think the number one rule is "Don't ask 'yes' and 'no' questions." Ask "how" and "why" questions.
I also found that, if one were so inclined, it's fairly easy to manipulate subjects into giving you the sound bite that you want. The chief videographer that I usually worked with, Keith, and I used to have a running bet as to whether I could get a subject to say exactly what I wanted them to, and I usually could. I found that subjects, especially ones that were not used to appearing on television, would often just repeat back to you the next to the last thing you'd say to them. For example, asking "Is this a new chapter for the city? What does this donation mean?" will elicit the response beginning "This is a new chapter for all of us...." We both found it amazing how often that worked.
And yes, some would say that's manipulating a subject, manipulating news. Yep, it is, and I really didn't care. It didn't take me but about 10 minutes in the business to realize that television news isn't journalism, it's show business. I delivered stuff that looked good and slick on the air, and was always truthful and honest... but it wasn't journalism, it was just show biz. I used to have a sign on my desk that said "I'm not a journalist, but I play one on TV." The station's general manager eventually made me take it down.
The next thing I found useful was the "talk about" question. I remember being in a gaggle of reporters once and this out-of-town reporter (I think it was a NASA story) kept asking the interviewee to "Talk about such-and-such...." I first thought "What a clunky and unprofessional-sounding way of asking a question." But then I noticed he got GREAT answers. I began using that, too... and it works well.
Fantastic Plastic Entertainment, Inc.