I collected video and audio from interviews with different kinds of users.
As an probing for qualitative information, my focus was to ask a generic opening question like:
"What they thought about the app?"
"What are some stories that other users or they can share with me?"
And then follow up with questions about their answers.
When I handed in the results of the first excursion, it was like the lights went on.
The insights were exactly what the company needed to see, more so than the UI changes that had been previously proposed.