Confidence, honesty, and a smile have always worked best for me. Having done a fair amount of contracting and consulting I have been on quite a few interviews and expect, in every case, to be asked questions to which I don't know the answer; when I'm the interviewer I like to have questions more advanced for the position just to probe for an upper level of competence.<p>Don't forget that an interview is a learning opportunity as well. Typically it's not just whether you can answer the questions with an academically correct answer but whether you can then re-state that in your own words with confidence. And if you don't know the answer, ask the interviewer what the answer is and write it down! This is good for three reasons: (1) it's a great way to learn what the interviewer thinks is important to know for the job, and (2) it could be a question someone else will ask in a future interview so writing it down and studying sets you up for successful interviews later, and (3) you might know the answer but not the correct name. For example: years ago on an interview I was asked to describe what the Factory Pattern was and said I didn't know. I then asked the interviewer to tell me so that I could study more about it as part of my professional self-study... but I realized from the description I had been doing this pattern but didn't know the name for it. I explained this to the interviewer, gave examples of when I used it in my code and why (and I got an offer after that interview too).