An entire book can be written on how to prepare for your interview, and many have. Here's a quick start for the new year that will get you in the right frame of mind.
You can never tell just what may be asked in an interview, but there are some basic questions that you can prepare for in advance.
1. Why do you want to work here?
2. Why do you want to leave your current job?
3. Why did you leave any of your previous position(s)?
4. What are your strengths?
5. In what areas do you think you can improve?
6. What are your longer-term career goals, aka where do you see your self in 5 or 10 years?
Prepare your answers to these questions in advance. I suggest writing them down in your favorite personal notebook tool. Mine is Evernote. Your goal is to come up with a very succinct response to each one of these, write it out, review them before the interview, and be able to speak extemporaneously on any if they're asked, without sounding like you memorized the answers. If what you have to say is true, meaningful, and directly answers the question asked, you won't have a problem.
It's essential to come up with the shortest possible answer for each one of these that will make the interviewer feel like you've provided a reasonable response that doesn't raise any red flags. It's better to make this answer too short, pause, and then ask, would you like me to elaborate on that? If they need more, they'll tell you, and if they don't, you just saved much time and probably gave them an answer they're good with. Remember, this interview is for them, not for you. Once they decide they may want to pursue you, then it starts to become for you as well. But you first need to elicit their interest and get them excited about you.