What's your best piece of advice for an Oxbridge interview?

Personally, going into the interview process, one of my biggest fears was not knowing the answer to a question and lapsing into silence. The best piece of advice I received before going into interviews was this: if you don’t know the answer to the question, just tell the tutors what you do know about that subject. The tutors will not be able to tell what knowledge you do have unless you tell them it. No one knows the answer to every question that is asked of them in these interviews and often the way that they must differentiate between candidates is how well the tutors feel they were able to help the student through a problem. If you give them somewhere to start, you make their job a lot easier!