Ask for past stories (‘what did you do’), not hypotheticals (‘what would you do’).

“When you went through that experience, what did you do?” rather than “If you ever got into such a situation, what would you do?”

You can learn much more about who they is from their past, than their ideas of how they hope they would respond in that situation. 

Additionally, in answering a hypothetical question, the responder can answer what they think is the right answer. It is harder to fabricate a story from the past.