I have a few tips for asking better questions:
1. Highly specific questions are better on average.
2. It is often better to preface a question with a confession of some sort, or with information from yourself. That sets a standard for the respondent. Set that standard high!
3. Demonstrate credibly that you are truly listening and that you care about the answer.
4. With any possible question, ask yourself in advance: can the person being asked the question respond too easily in a vague and not very useful way? “Why did you write a book about Napoleon? Well, let me tell you, French history always fascinated me.” etc. If that is the kind of slop you might get back in response, try making the question more pointed or more specific.
5. High status people get better answers than do low status people. So be high status. Or at least credibly pretend to be high status.
6. I have enjoyed Gregory Stock’s The Book of Questions.
7. You might say “listen to other interviewers.” Well, maybe, but perhaps not too much? They will encourage you, by default, to ask the same questions that everyone else does. And too many of the sources available to you are mega-famous people who are getting by using their fame to boost the significant of their questions. (Anything Oprah might ask me would be interesting per se.) So use this standard tip sparingly and with caution.