How can a qualitative researcher collect the data in the form of narratives (usually) from people who are expounding on their experiences?

How can a qualitative researcher collect the data in the form of narratives (usually) from people who are expounding on their experiences? What happens if the data the researcher collects and analyzes is biased to begin with? How can the researcher take measures to prepare to make sure they hear the participants' voices and also report that clearly?

Hint: look at bracketing.