I'm a corporate trainer and just finished (about 5 hours ago) teaching a class on how to conduct an interview so I can offer a little advice on interviews.

The biggest, and most frustrating, piece of advice I have is to tell you that everyone wants something different out of interviews and the interview questions. This is why it is good to get to know a company before going into your interview. Depending on the kind of place you're going to you can arrive a little early for your interview and talk with the receptionist/employees about their experience working here. Most of the time they will be honest with you and you can get a feel for the manager/culture of the place you're interviewing at. That said here are some notes from my class earlier:

• The best interviews are conversations. If the person interviewing you has any skills whatsoever they will be able to handle the interview like they were just chatting with you rather than an inquisition. This can also fall back on you. If you simply answer the question and then get very quiet the interview can turn into just a call and response scenario.
  
• Avoid buzz words. Nothing is more upsetting to me when I'm interviewing someone and they say "I'm a hard worker, dedicated employee, and great with people." All that sounds nice but it doesn't mean anything to me. Try instead to say "I've always been a hard worker. I've dedicated myself to the same job for the past 3 years. I've worked hard at expanding my knowledge by doing X, Y, and Z. My boss would frequently comment on how my work was always above standards." Give examples when you describe yourself.
  
• "What is your greatest weakness"- The dreaded question. I always hate answering this question in interviews and love asking it when I am interviewing someone else. The problem with this question is that you do not know what they are looking for with it. I can't really tell you what everyone is looking for in an answer because that changes from person to person. When doing an interview though, I look for honesty without the flaws that are going to negatively affect my team. I do not need people on my team that are going to be late, have trouble with details, etc. My best advice is to pick some skill you wish you did better and talk about that. My answer to this question is usually along the lines of "my greatest weakness as a trainer is my limited experience with e-learning. It is a new learning technique that I am interested in learning more about and possibly in the future developing a few online courses for my employees." Then I would ask if this company was using distance learning technology and if they had any plans to move in this direction.
• No matter what, do not trash talk you old job/old boss. It does nothing but make you look petty.
• When asked if you have any questions, always have a few questions ready. They can be about the company, job, culture, management style, etc. When you say you don't have any questions, it can make it sound like you're not that interested. I personally am usually not upset when people don't have questions, but I have sat through numerous seminars with people you are likely to interview with who care very much about this question. My favorite question to ask and be asked is "do you have any reservations about my candidacy for this position" or something similar. It gives the interviewer the chance to clarify a point that might have given them hesitation or let you know their thoughts on your ability to fit into the job.
• Be as honest as possible. You don't want to throw yourself under the bus with honesty, but you also do not want to mislead your potential new boss. I usually get lied to when I ask what motivates someone to perform well at their job. They usually tell me what they think I want to hear (aka work is it's own reward, helping people makes me feel great, etc). One of my best employees told me straight up she is motivated by money and the chance to earn more of it. And that is exactly how I motivate her. Now if she told me she is motivated by building relationships with clients then I would probably find a way to reward her for positive feedback from clients.
  
• Make yourself memorable. This is especially true if you're applying for a job that a lot of people can do. One of the things I put on my resume is that I used to teach ballroom dancing. Every single interview I had since putting that on my resume wanted to talk about that experience and how much they enjoy watching/doing ballroom dancing. It makes me memorable and more likely to get called up for a 2nd interview. In fact, my interview for the company I for now was almost a 40 minute discussion about ballroom and 20 minutes of answering questions. They hired me 2 days later.
  
• Make a great first impression. I recently read a statistic that most interviewers decide within 14 seconds of meeting you whether or not you're a serious candidate. Dress nicely, get a hair cut, smile, give a firm handshake and appear as relaxed as possible. You're selling confidence. Even if you're not confident, pretend to be. Try to be personable and if you can make you interviewer laugh. They're sometimes as nervous as you are!
  

Now as I said, these are not universal rules. Try to understand the company you're interviewing with is the best way to know how to prepare for an interview. You can also do some research on best "how to conduct an interview" books and read those because that is what your interviewer is likely reading.

Hope this helped some and best of luck!