Be well groomed. Clean hair and fingernails are essential.
Dress appropriately. Your clothing should be appropriate for the position you are seeking.
Wear comfortable business attire.
Abstain from chewing gum or smoking.
Do not wear perfume, cologne, or other strong scents. Some interviewers may have a sensitive nose.
Relax and try to enjoy the interview. If you are not yourself, it will show.
If the interviewer feels that you are comfortable, this will ease the tension... for the both of you.
Try not to be too "scripted" and remember to adapt to the conversation.
Make sure you understand the process. Different employers may have different hiring practices.
Find out as much as you can about the position, the organization, and the industry.
Try to enquire about the name of the interviewer beforehand and research on his or her background.
Talk to colleagues and friends who are connected to the employer.
Know your strengths and weaknesses.
Understand what your strengths and skills are and how best to highlight them through examples.
Know the qualifications and requirements of the job and be prepared to show why you are the best fit for the position.
Identify your employer's practice areas, culture, size, corporate philosophy, opportunities for growth, etc.