I just participated as an interviewer for some of the students applying for admission to the Sports Administration Program here at Ohio University. One of the things I noticed quite a bit was that of the five candidates I interviewed, several of them never answered the question I actually asked them. It was a bit annoying, really, and something that stuck out as a negative for me in evaluating them.
I know interviews are nerve-racking and can get a person flustered, but make sure you concentrate on what the interviewer has asked. Anyone in an interview should carry a portfolio with a notepad in it. Write down the question if you have to or put quick notes about what you want to cover in your answer. If I saw someone do that it would actually indicate to me that they're thinking (quickly) about what they want to say and not just rambling freely.
Also, think about what person you use when you answer questions. I write this blog in second person intentionally. I write it as if it's written to an individual student ("you" this or "you" that). When you're in an interview, and you get asked a question "What would you do...," don't answer it in second person. I, and most interviewers, want to know what YOU would do. Answer it in first person. If it's a generic question, then answer it in third person ("a person would have to..." or "one might..."), but don't try to tell me what I would/should do by using the word YOU.
Lastly, try to avoid generational words. Take "like" out of your vocabulary during interviews. It's become as annoying as "um" that happens while people are pausing. "Awesome" is an over-used generational word, too. If you have to, look up some other descriptive words in a thesaurus. A good grasp of other adjectives leads me to believe that you're educated, well-rounded, and more mature than others. Whether it's true or not doesn't necessarily matter. It's how you come across in the interview.