I just finished interviewing several candidates for a position I have open. In this day and age - people expect to know why they didn't get hired - most especially college graduates. So here's some advice I have going into the interview.
1st and foremost always exhibit confidence. Approach an interview as if you are selling something - Yourself! I bring examples of my previous work along. Whether it's the book I helped write or some documentation from my last project. The whole idea here is convincing the interviewer that by choosing you they will get the best ROI! (Return On Investment)
If you don't know the answer to a question have a strong supporting backup answer. How would you go about finding the answer? What resources would you utilize to determine the correct answer? 90% of the time the interviewer is looking to understand how you think and how you act on your feet.
Don't be afraid of failure - without failure you simply don't learn things in life. The questions I ask are standard interview questions all picked up from Google - learn a solid answer for these types of questions and again stick to that answer - personal answers are not the best answers. Interviewers are more interested in how you handled something on the job - be it college, senior project or an after school job.
Listen to the interviewer - they often give hints in their questions as to how they want you to answer them back. It could be within the question they are asking or it could have come in the discussion of a previous question.
Don't put it on your resume if you can't answer the question. It amazes me that people still do this. If the technical grilling doesn't catch it in the interview you will fall down on the job and then everyone knows it.
And finally read the job description closely - notice the hints as to what they will be interviewing you on. Create an outline of the necessary knowledge before the interview - I often make a multiple page review sheet before I go to an interview that refreshes me on the different questions that could arise from my resume and the job description.