The question also brought out quite a bit of interesting criticism of other breeds. Make comments that show your sympathy for your subject's point of view or interests. For example, if you are interviewing a dedicated country doctor, you might comment on how few physicians are willing to make house calls any more and how unfortunate this is. If you are talking to a computer scientist, you could say how exciting it must be to work in such a fast-moving field. During the interview itself, take only what notes are necessary to get the facts straight.
Writing makes many people nervous.
This, of course, depends on your topic. If, however, you are after general information, you can catalogue the material in your mind. Then right after the interview, put them down on paper. Use your subjects as sources of more persons to consult. Usually an expert will know the names of other experts in the same or in related fields.