You may have 10 A*s at GCSE, 5 As at AS level and a top notch personal statement but if you mess up the entrance exam, this could all count for nothing.
So whatever you do, don’t get so wrapped up in stressing about the Oxford interviews that you neglect the important steps leading up to them.
Your personal statement may go into great depth about your knowledge of mechanical engineering but for all the tutors know your great uncle Robert could be a lead engineer who has written it for you. Your entrance essay on the rule of Henry VIII might be absolutely fascinating but for all they know could be written by your mum who happens to be a history professor.
Oxford want to see YOU and initially, this is where the entrance exam comes in.
The idea is that you can’t really revise for the entrance exams as you have no idea what is going to come up. This is intended to put everyone on a level-footing. What you can do though, is practice writing on or thinking about unseen material.
Top Tips
Take one step at a time; focus on the entrance exam before getting super stressed about interviews.
Not all subjects require an entrance exam, check online to see whether yours does:
https://www.ox.ac.uk/admissions/undergraduate/applying-to-oxford/tests?wssl=1
Make sure you register to sit the exam on the date scheduled by Oxford. Click on register under your subject in the web link above.
Arrange either to sit the exam at your school or at an authorised test centre.
If you miss the sitting, your application may not be considered.
Print off journal entries, maths equations, tables, graphs, poems, newspaper articles and prose relating to your subject. Give yourself a time limit in which to answer, analyse and annotate them.
Make connections between these unseen passages and other sources of which you have prior knowledge.
Download some of the past papers online and observe the sorts of questions which come up and how the papers tend to be structured:
https://www.ox.ac.uk/admissions/undergraduate/applying-to-oxford/tests?wssl=1
Note down common themes and think about them in relation to your subject.
Have a look at some critical thinking papers online; these are useful for practising your close reading and analytical skills.
Study any relevant theorists and terminology which might be applicable to your subject.
If you are doing an essay subject, learn a few critical quotes which could be used in a range of essays. For instance, for English I memorized the Wittgenstein quote ‘the limits of our language are the limits of our world’.