How should I prepare for an Oxbridge interview?

Vying away from the simple 'be yourself' or 'be passionate about your subject' which are both terribly vague and difficult concepts to teach, the simplest and best secret I can give to anyone applying for Oxbridge is that the interview is nothing to be afraid of - seemingly impossible to believe, I know. But for any Director of Studies at Oxbridge, the interview is a way for them to see if you would fit into their supervision/tutorial system, the main different component of undergraduate studies at Oxbridge. They are trying to see if you would work well, and flourish, as they would want for anyone, under their teaching style and their preferred focuses in these sessions very similar to the interview once to four times a week. There's not much you can do to control this - seems scary right? However, your interviewers are not there to scare you, they're not there to break you, they just want to see how you think; so if you don't know, ask, if you're confused, say, if you're guessing something, let them know, and they can guide you. Every interviewer wants you to do the best you can in the interview, though they might not seem like they do at the time. So all you have to do is breathe, relax your shoulders, listen carefully to what the question is, and think BEFORE you answer. Though this is not a surefire way to ace your interview (trust me, there isn't one), it's the best way to make sure that you do the best you possibly can, and show off all the preparatory work you've done.