Ask open-ended questions like how and why [FILL IN THE BLANK] happened.  Simple questions get simple answers.  Open-ended questions get bigger, more interesting answers.

Give something to get something.  Interviews work better when it feels like more of a conversation or exchange.  I try to give something back to the people I interview, even if it’s a minor anecdote, and I try to respond to what people tell me.

Compare and contrast.  What was your childhood like is an okay question, but getting someone to contrast their childhood with yours might get you more interesting answers.  The 20th century saw huge changes in how people lived around the world – reflecting on that is a useful way to learn about how your family once lived.

Don’t break the silence.  No one likes an awkward silence, and people will eventually fill that silence.  The great journalist Robert Caro got some great material for his books by reminding himself to shut the “f” up.  Allow time for people to think.  You want your subject to talk more than you do.

Actually listen to the answer and ask the follow-up.  An outline is meant to help you get your subject talking, but you should be listening to what your subject says and hopefully have a conversation.  Get some detail that helps bring the scene to life. 

Repeat things back to make sure you understand what the person said. If you’re not clear about what someone said, say what you think you heard and ask if you have that right. This can clarify answers and maybe spark some additional details.