1. Do a lot of guest research - people love it when you take the time to understand their past experiences and ask questions about them. Bring up any points from their story that the audience may be curious about. Find obscure details, read their entire bio, watch existing content they've produced, and consume any of their work - it will help.
2. Ask your open ended question, and then shut up - remember, when you host an interview-based podcast, it's not about your story, but that of your guest. You don't need to inject your own opinion into every little thing. Do enough to have a fun exchange.
3. Follow up. Always ask why, or find a way to make whatever they say helpful to your audience. They might not know intuitively to give practical advice, or the way they tell the story might not point that way, but you can definitely solve that by just asking.
I've done marketing, UX research, and a lot of podcasting before and these have helped me most!