You cannot have a remunerative, even intelligent, conversation with people about something they take as self-evident if you give them the impression you regard their belief as an illusion (Edward Evans-Pritchard, in Shweder 1996).
There are a variety of approaches to qualitative interviewing, which vary according to how unstructured the interview protocol is and whether there is a common stimulus the respondents have experienced. These range from completely unstructured ethnographic interviews to structured, in-depth interviews (see Bauman and Adair, 1992, for a good typology).
References:
Anderson, E. (1978). A Place on the Corner. Chicago: University of Chicago Press.
Ash, P., Kellermann, A. L., Fuqua-Whitley, D., & Johnson, A. (1996). Gun Acquisition and Use by Juvenile Offenders. Journal of the American Medical Association, 275(22), 1754-1758.
Bauman, L. J., & Adair, E. G. (1992). The Use of Ethnographic Interviewing to Inform Questionnaire Construction. Health Education Quarterly, 19(1), 9-23.
Brown, G. W., & Harris, T. O. (1978). Social Origins of Depression: A Study of Psychiatric Disorder in Women. New York: Free Press.
Liebow, E. (1967). Tally's Corner: A Study of Negro Streetcorner Men. Boston: Little, Brown and Company.
McCracken, G. (1988). The Long Interview. Thousand Oaks, CA: Sage.
Merton, R. K., Fiske, M., & Kendall, P. L. (1990). The Focused Interview: A Manual of Problems and Procedures. (second ed.). New York: Free Press.
Spradley, J. P. (1979). The Ethnographic Interview. New York: Holt, Rinehart and Winston.
Whyte, W. F. (1955). Street Corner Society: The Social Structure of an Italian Slum. (2nd ed.). Chicago: University of Chicago Press.
Williams, T. (1992). Crackhouse: Notes from the End of the Line. Reading, MA: Addison-Wesley.