It all depends on the kind of interview.
Let assume this is an insurance-related claim interview; If this is the case, review over and over all the ducuments submitted with the claim regarding the loss, the alleged injuries, etc.
The first one to be interviewed is the client, adjuster or attorney. Get the cleint's concerns
When interviewing the subject or claimant, have him/her lay his/her version without any interruption even if you do not believe the story.
If discrepancies are detected, have him/her clarify or repeat the version before confronting the subject with facts.