4x 20-40 min interviews, 2 hrs apart
Interview 1: motivations, personal statement, work experience; Interview 2: science (diagrams)
Practice papers, mock interviews
Stay calm; try to enjoy yourself.
Remember this advice isn't official. There is no guarantee it will reflect your experience because university applications can change between years. Check the official Cambridge and Oxford websites for more accurate information on this year's application format and the required tests.
Also, someone else's experience may not reflect your own. Most interviews are more like conversations than tests and like, any conversation, they are quite interactive.
Test taken: BMAT
Number of interviews: 4
Skype interview: No
Time between each interview: 2 hours
Length of interviews: 20-40 minutes each
In my first interview we discussed why I wanted to study medicine, as well as my personal statement and my work experience. We also discussed why I wanted to study at Oxford and the sort of things I would enjoy doing whilst in Oxford, such as clubs and societies.
In my second interview the focus was on science; I was presented with some diagrams and asked to pick out a feature and talk about it in detail. The interviewers used my answers to ask me more questions, so that it was more of a conversation, rather than me reciting information.
To prepare for the test, I used the practice papers.
To best prepare for the interview you need to know about the subject you are applying for as a whole in terms of what qualities it requires from you and what it entails.
Retrospectively I would say that, if an applicant has made it as far as interview stage, then you have what it takes to receive an offer. Just stay calm during the interview and show the interviewers your desirable qualities, such as resilience and coping under pressure, but also try to enjoy yourself. (I know this sounds absurd.)