Know the format of your thesis defence
The format of the defence varies from country to country. Having studied in the UK, my viva-voce defence was essentially an interview with one internal and one external examiner. In other countries it’s common to have public examinations with a whole panel of examiners and an audience of colleagues, family and friends.
The first and most obvious tip then is to make sure you know what the format of your exam will be; whether you will have to prepare a presentation and so on.
Prepare and practice your presentation
If you have to give a presentation, check any time restrictions so you can prepare accordingly. You don’t want to show up with 100 slides for a 15-minute presentation, nor do you want to show up with 10 slides for a 1-hour presentation.
The most important thing to do for any presentation is to practice so that;
You know the material inside out
You know how long it takes
You can refine the presentation
You can practice on your own and with an audience, and you should do both if possible. Practicing on your own and speaking out loud to an empty room may feel silly, but overcoming that discomfort is good preparation for the discomfort of facing an actual audience.
Practicing with an audience of peers is then a good way of getting feedback and finding out what questions people ask.
The dreaded “awkward question”
Whether you have to give a presentation or not, one of the scariest aspects of the defence is the possibility of being asked a question you can’t answer.
It’s tempting to try to read a ton of literature to prepare for this, but since it’s very difficult to predict what the examiners will ask and it’s impossible to read everything, this approach isn’t always effective or reassuring (it might make you realise how much you don’t know).
There will always be gaps in your knowledge, but actually it doesn’t matter if you don’t know the answer to an awkward question- you can still respond in a way that will make the examiners happy.