Research the Company
Make sure you research the company before you go for your interview. Go to the company webpage and read press releases. Conduct a web search and find out any recent news from the company. Displaying knowledge of the company is a way to let the interviewer know that you are serious about the position.
Dress the part!
One of the first things that an interviewer will notice and use to evaluate you is how you are dressed. It's important that you show up looking your best. For men, a suit, pressed dress shirt and tie are standard interview attire. If you don't own a suit, then a collared shirt and dress pants are a good alternative. Women should wear a clean, pressed blouse and suit or skirt. Even if you are applying for a job in a casual office environment it is better to be overdressed than underdressed. Never wear shorts, jeans, or athletic shoes to an interview.
Be on time
Make sure you have directions to the location of the interview, and if necessary do a trial run so you know how long it will take you to arrive. You should arrive at the interview location 10-15 minutes before your scheduled interview time. Arriving more than 15 minutes before your scheduled time should be avoided, since some interviewers see this as being disrespectful of their time and ignoring your appointment.
One thing that all interviewers hate is when they ask a question and receive one or two word answers. Take the time in an interview to talk about yourself and why you are a great candidate.
Write a thank you card
When you are done with your interview make sure you get a business card from your interviewer. The day after your interview send a brief thank you card or email to the interviewer to thank them for their time.