1. Enter into a state of relaxed concentration.  You'll need to quiet the negative self chatter in your head through meditation or visualization prior to sitting down in the meeting. You'll focus on the present moment and will be less apt to experience lapses in concentration, nervousness, self-doubt and self-condemnation. 

2. Act spontaneous, but be well prepared. Be your authentic self, professional yet real. Engage in true conversation with your interviewer, resting on the preparation you did prior to coming to the meeting. Conduct several trial runs with another person simulating the interview before it actually occurs. It's the same as anticipating the questions you'll be asked on a final exam. 

3. Set goals for the interview. It is your job to leave the meeting feeling secure that the interviewer knows as much as he  possibly can about your skills, abilities, experience and achievements. If you sense there are misconceptions, clear them up before leaving.  

4. Know the question behind the question. Ultimately, every question boils down to, "Why should we recommend you?" Be sure you answer that completely. If there is a question about your meeting deadlines, consider whether the interviewer is probing delicately about your personal life, careful not to ask you whether your family responsibilities will interfere with your work. Find away to address fears if you sense they are present.