This indicates to the employer how well you would prepare on the job. Find out as much as you can about the company. Come prepared with discussion topics and how you can help this particular company. Be prepared to play by the company's rules. They may require you to interview three people in one day or they may make you stay for three hours.
Every company is different, so be prepared to adjust to their interview habits.
Plan how you will dress for the interview. Allow sufficient time for the interview. Arrive at the interview early. Keep a positive frame of mind. Plan to go to the interview alone.