Do pay attention to your personal grooming and cleanliness.
Do know the exact time and location for your interview.
Do arrive early: at least 10 minutes prior to the interview start time.
Do treat all people you encounter with courtesy and respect.
Do offer a firm handshake.
Do show a positive attitude during the interview.
Do maintain good eye contact during the interview.
Do respond to questions and back up your statements about yourself with specific examples whenever possible. Ask for clarification if you do not understand a question.
Do be thorough in your responses, but do not ramble on forever. Be concise in your wording.
Do be honest and be yourself. Dishonesty gets discovered.
Do exhibit a positive attitude. The interviewer is evaluating you as a potential worker.
Do have intelligent questions prepared to ask the interviewer. The interview can be a two-way street. You can ask what kind of employee they are looking for and return with an explanation of how you fit that description.
Do send a thank you letter after your interview.
Interview Don'ts
Do not wear clothing that is wrinkled or too revealing/low cut.
Do not wear a lot of jewelry.
Do not make negative comments about previous employers or others.
Do not falsify application materials or answers to interview questions.
Do not arrive late.
Don't give the impression you are only interested in salary; don't ask about salary and benefit issues until your interviewer brings up the subject.
Do not act as though you would take any job or are desperate for employment.
Do not be unprepared for typical interview questions. Being unprepared appears as if you do not care about the job.
Do not refer to the interviewer as "Dude" or other slang terms.
Do not go to extremes with your posture, don't slouch, and don't sit rigidly on the edge of your chair.