Some good posts are already here and really interesting insight.
Before you face an interviewer, go through your resume very carefully. Learn what you have written in it by heart because most of your questions would come from that. Keep the objective of the job in mind and be prepared to support your candidature with logic. Don't simply say that you are the best guy for the job but be prepare to show why.
It is also important to learn to turn the negatives in your resume to your favor. If you were out of job or have been laid off, have your explanation ready.
Lastly, take control of the interview and don't the interviewers dwell much on unimportant things.