The unique teaching method in Oxford and Cambridge is the Supervision - this is a regular one-to-one or two-to-one discussion with an expert in the field on and around the subject matter. These supervisions are fast-paced and quite intense, and challenge you to think deeply about the topics you're studying. The purpose of the Oxbridge interview is to test how ready you are to adapt to this supervision environment. They don't care whether you've memorised all available facts on a subject, they want to see how you respond to being asked difficult questions on unfamiliar ground. There are simple ways to do well in this process:

 - Explain your thought processes and how you go about solving the problem. Your use of a good method to answer a difficult question is what they're looking for; not necessarily the right answer.

- Be honest in your answers. Don't guess at random solutions which you can't explain; if you get something right they'll likely ask you to apply the same logic to a new unfamiliar problem.

- Keep calm and be keen. If you try and enjoy the challenge of the questions they pose, and appreciate it as an opportunity to discuss the subject you're interested in with experts in that subject, you'll look like the type of person they're after. The whole place is based around the ethos that challenges are good things, anyway.

So before your interview, make a point of seeking out some of the more complex and hard to explain concepts or processes in your field of study, and have a go at explaining them in a calm and cogent manner to someone. Practice being inquisitive, but most importantly practice explaining solutions to problems in clear and logical steps.