There are a lot of steps that usually happen before you get to the interview portion of your job search: writing a resume, networking, compiling your references. Most folks are able to put a lot of effort into getting the interview, but many fall apart during the actual interview. Why? Poor planning and a lack of practice.
Instead of winging it, or relying solely on your professional skill set, you should stage a rehearsal for your next job interview. Not sure how to go about doing so?