Saying this I suggest you do some research on the potential employer's business/company. If you know the story behind the business, the interviewer may be impressed and you may build rapport making the interview go a little smoother, which is always a good thing. Also be prepared to answer questions such as why you want to work here, what makes you think you could be a valuable asset to this company, and a little about your work history; Having the answers to these questions ahead of time will allow you to produce quick answers on the spot making you appear to be the stronger candidate. Clothing is also an important but simple topic to remember, you don't want to be that guy who arrives at an interview with an IT technician wearing shorts and flip flops. You have to dress for success, and by dressing for success I'm implying that you should dress like a professional, even though for some people appearance doesn't matter; you have to remember that you are the face of someone else's business and you have to look as serious as you want