2x interviews
Interview 1: discussion of a newspaper article, then questions on personal statement; Interview 2: questions on written work
Reading, thinking critically about it, and essay competitions
Read as much as you can about things you are interested in, and practice talking about them
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: None
Number of interviews: 2
Time between interviews: about 10 minutes
Length of interviews: about 15 minutes
Online interview: Yes
In the first interview, I was given a source — in my case a newspaper article — and I was asked questions about it, to summarise it, give my thoughts etc. I was then asked about my personal statement and in particular the books I said I had read. I was asked questions about whether I agreed with the authors and prompted to talk about them critically. All in all, not many questions were asked, since I was the one doing most of the talking and it didn't last very long.
In the second interview, I was asked about the two essays I had been asked to submit for the application process. These questions ranged from the specific to the general.
I read, read and read. I read daily and for multiple hours. In particular, I made sure I had read a wide range of books which reflected both a willingness to challenge myself and a general curiosity. I also kept up with the news. Read as much as you possibly can, and try to think intelligently about what you've read. I also entered a couple of essay competitions, one of which I placed 2nd in.
Read as much as you can. This is easily the most important thing you can do. Make sure what you're reading is what you are interested in and involves things you can talk about at length. If you can't discuss a book you have read at length, do not put it in your personal statement. If you struggle to remember what you think about books, make notes on them. Read books that have some relation to each other — if you've read a book by Foucault, it would be helpful to read another book which takes a different viewpoint, or which has interesting things to say about him. Pursue your reading based on what you find interesting.
Make sure you think independently about what you have read — do not just repeat uncritically what others have written. Perhaps discuss what you've read with anyone you know who would be interested to hear it, or write down your thoughts. I cannot stress this enough — you can have as much interview practice as you like, you will always be disadvantaged compared to someone who has read much more than you. If you have read a lot, and can talk intelligently, thoughtfully and with real enthusiasm about what you have read, then that is more than enough to do well in the interview.