NJ-12 is crazy competitive. When you go to the interview, bring a copy of whatever you already mailed in as sometimes paperwork gets lost. Practice interviewing skills. A firm handshake and good posture are important. Dress professionally.
My son received a nomination from Lance, who was a pleasure to work with. His office staff was well organized and prepared for the interviewees. We had not met him before this process (so no, he didn't nominate my son because we knew him or donated money to his campaign).