Show courtesy to everyone during the interview. This means everyone from the reception staff to the interviewer herself. You never know who has input in the hiring process, and you can only make a first impression once. Look everyone in the eye and smile. Looking people in the eye will telegraph alertness, and smiling will signal friendliness. Speak clearly and say "please" and "thank you." Make sure the people you talk to during the interview can make out what you're saying