Don't mention about your idea as far in the conversation as possible!
Rules:
- Talk about their lives, not about your idea;
- Ask about the specific things from the past, not about hypothetical opinions about the future
- Talk less, listen more;
Golden rules:
- Opinions are useless.
- Any predictions about the future is a lie, usually overoptimistic.
- People know about the problems they face, but don't know how to solve them.
- Know the goals of your user
- Some problems in fact are not problems
- Watch your users in real life solving their tasks
- If users didn't try to solve this problem before, they wouldn't pay attention to your product.
- Ask question: "Who else I should talk to?", "Are there other questions I should ask?"
- Avoid compliments at all costs.
- Analyze requests for new features.
- Ask tough questions! You need the truth! It's wonderful if the response is negative!
- Thus unemotional answers "well, .. seems not so bad" are better than "WOW!" answers (they give more info, wow-answers are unreliable).
- With high product risks - you need to start developing, you cannot prove your business idea just from the interviews. You have to embrace them.
- Prepare top 3 questions for any interview (to make them productive).