In the field of investigative journalism, a solid background in interviewing often spells the difference between a good journalist and a great one. To achieve the best results, you should try to conduct interviews in person as much as possible; in addition to providing you with the opportunity to pick up on nonverbal cues from your subject, in-person interviews tend to encourage interviewees to be more forthcoming in what they divulge.
When preparing for your interview, pay careful attention to the background of your subject. If you are to interview an expert in a field, be sure to do your homework and avoid asking questions that can be answered with a simple Google search. If you conduct an interview with vulnerable people, be sensitive to their feelings and avoid pushing them too far out of their comfort zone. In terms of questions, go in to the interview with a set list, but don’t be afraid to improvise based on how the interview proceeds.