1) Do not be late. It is nearly impossible to recover from the negative impression created when you are not on time. If 
you can’t get to the interview on time, the employer will likely question your ability to get to work on time. If there is a true emergency, call to reschedule the interview if possible.
2) Do not monopolize the interview. Rather than filling the time with endless chatter, it is crucial to listen carefully to the questions you are asked and to respond with clear, focused answers that highlight your skills, education, and experiences as they relate to the position. The best interviews are two-way conversations.
3) Do not focus answers on:
- Hobbies, recreation, vacations
- Politics, religion, current social issues, or other “hot button” issues
- Relationships and personal lifestyle choices
- Medical problems and health issues
- Personal topics that bear no relation to your professional life
4) Do not speak unkindly of past employers. It may seem like the interviewer is sympathetic to how poorly your former employer treated you, but in the back of his/her mind there is a concern that some of the blame may be yours. There is also an awareness that if hired, it may not be long before you start complaining about your current employer.
5) Do not mention salary first. This may be a burning question for you, but if you follow interview protocol, you’ll wait for the interviewer to raise this issue. If asked, be sure you’ve researched the salary range for the position and also what you believe you are worth based on your credentials. Be ready to give a rationale for how you arrived at your numbers.
6) Do not cross the line from self-assured to self-obsessed. No one wants to work with an obnoxious know-it-all.