We go into an interview knowing nothing and hoping to know everything when we come out the other side. As a result, it's easy to ask a whole bunch of questions all at once. By the time we've finished our line of questioning, the participant will likely be overwhelmed. So they will end up answering only the last question asked or the one they remember best, leaving a whole bunch of questions unanswered in between.

Instead, use self-restraint to ask just one question at a time. As soon as you hear the metaphorical question mark leave your mouth, close it. Let the participant fully respond before you ask the next question. This will allow you to control the rhythm of the conversation and create a much more fluid back-and-forth.