Ask questions to establish your subject. Researchers are there to facilitate the interview, but consider that the one being asked has all of the answers. If working with a focus group of people, some characteristics such as gender, age or nationality may have been controlled for. If not, it is important to know what kind of lens that answers are coming through. Ask about the person's situation to set the stage; knowing who the person is can help to explain why something is more or less important, acceptable or distasteful to them. Asking for information in a way that encourages elaboration is ideal; questions like: "Tell me about your nationality," "What is your living situation like?" or "Have you lived here all your life?" help to establish basics about an individual. For instance, if you are doing a study about changing locations during midlife, answers will differ considerably depending on whether the individual is single or a couple and living above or below the poverty line.
Be flexible. Becoming determined to prove one certain point can undermine the whole purpose of qualitative research. Instead, be prepared to learn from answers and shape the direction of the study from them. It can be difficult to develop unpredictable research questions on the spot, but some questions that fit with the idea of qualitative research are "Please explain further," "Why?" and "What do you think about that?" Keeping the question open-ended is most important, and the focus should be to have a thorough understanding of someone's perception about an issue by the time the interview is through.
Stay in context of the study. One of the first things to be established is whether the person has the kind of information you need. If doing a study about technology use in young adults, you will want to know whether the young adult in question uses a computer often. Ask questions that aim to discover what people mean, need, or desire in the context of your study. What they think has led to the phenomenon you're discussing, what they think the future holds for the phenomenon, and how they think other people perceive the phenomenon can all be linked via different comments that someone might make.
Ask questions that don't suggest a "right" answer. Even open ended questions can suffer from creating a bias, something that can lead people to answer with what the researcher would like to hear instead of with their opinion. Avoid comments like "Isn't it?" and "Don't you?" as well as questions that require only a "yes" or "no" and disparaging or suggestive words or phrases.