Great question! Here are some example questions:
- What do you do? - After some small talk, just ask them directly about their work! Usually, they'll answer with something that'll prompt more questions like "oh, what is [thing they mentioned]?" or "how has [project they mentioned] been going?
- What do you enjoy most about your job?
- What's the most challenging part about your job?
- How did you get into this field?
- If you could go back and do anything different in your career path, what would you change?
- How do you see this field changing in the next 5-10 years?
- What do you do on a daily basis? What does a typical day look like?
- What advice would you give someone who is considering this type of job (or field)?
Google "good questions for informational interview" and you'll get some more great questions!