Just keep in mind that you know more about your thesis than someone else including your examiners.

I just passed my viva with minor corrections (6 weeks) this Monday. It seemed that the examiners asked a lot of
questions using the word "Why". E.g. Why do you measure variable A in a particular way? In addition, if your study is based in a special context, e.g. you choose a partiluar country, think about the features of your context, how does it differ from the others. In particular, if your examiners are not very familiar with your research context, they might want to clarify something. Finally, be clear about your data if you are doing quantitative research.

I hope this would be helpful.