Be confident in the lab.
Always you have to clear about your answer.
Maintain an eye contact and be respectful.
Approa your answer in a positive way.
Don’t be scared
Feel free to ask question of you don’t understand.
Be gentle and polite in behaviour.
Always let the supervisor complete speaking first.
Relax.
Understand the question and answer to it.
Don’t try to answer to the question which you don’t understand clearly.
Formal dressing style matters.
Respect and wish the invigilators.
Be polite to them.
Good behavior also matters.
For me personally, its all luck.
Sometimes you think your viva went bad and you end up scoring good.
Sometimes you think you aced it and then you see yourself nearly passing it.
To score good marks in a viva, know your thesis/project thoroughly.
Prepare for common questions and practice your responses.
Stay calm and composed, and listen carefully to the questions.
Be honest and transparent in your answers. Show enthusiasm and passion for your subject to demonstrate expertise.
Good apron
Well groomed
Wishing examiners
Touching only those points which you know