Listen to the language and speech of the interviewee! Remember that the Latvian language has four dialects and many sub-dialects. In addition, you will rarely meet a speaker with a «pure» dialect. People move during their lifetimes and often appropriate impressions from their surroundings in their vocabulary, intonation and even their manner of speaking.
It is interesting that immigrants who speak other languages appropriate the features of the Latvian dialect from the place where they settled. For livelier, more natural and clearer memory narratives of people of other nationalities, interview them in their native language.
Not only is what you ask important, but also how you ask questions. They must be clear and simple.
People sometimes limit themselves to general answers or think that details are unimportant or boring for the listener. But each specificity can recall a number of other details that you as an interviewer might not have thought to ask.