asked a question that is not related to your subject. instead of struggling to find a good answer, simply say that you do not have good knowledge about that particular idea.
smile. whenever one of them is asking a question or demanding an answer, smile. this will show them that you are prepared and ready to communicate.
write down some ideas that you want to explore. it might come in handy to have some papers ready if you are stuck or you feel that you forgot everything. this happens even to the best of the best.
mention your personal experience. if the topic is right, and you can mention something that happened to 