I got into interviewing this last year as an interviewer. I used to think (as most people do) that the interview is a confrontation between interviewer and candidate.
However my biggest breakthrough happened when I changed my perspective. Now I see interviewers as detectives, gathering evidence of whether the candidate would be a good hire.
So my advice to candidates is the following: don't think of the interviewer as the enemy. Usually they aren't trying to get you, but help you. And if that isn't the case, you don't want to work for that company anyway. Keep a friendly and relaxed conversation with the interviewer and you'll be surprise how far it can get you.