Do your homework before going on an interview. Educate yourself about the company and prepare questions and answers based on what that company or organization does. Never ask, "What does your company do?"
Try to use appropriate terminology in the interview. That will make you stand out from the rest. Also, asking questions of an interviewer shows that you are engaged and interested in the position. Never ask questions that are clearly answered on the company's Web site. This just says that you didn't prepare for the interview. Some of these questions might be answered during the interview [source: Virginia Tech].
Of course, it should go without saying that you should never, ever ask inappropriate questions during your interview, but then I got this gem in an e-mail from my editor. "I had a guy ask me how many 'hot chicks' worked at the company." Really?