How to handle questions when presenting
To deliver a presentation in a convincing way you need to feel and show confidence. What often weakens that confidence is actually not the presentation as such - it is more the fear of questions from the audience. You need to be well prepared and know your topic but you also need to handle the questions well.
Hint no.1: Listen - really listen - to the question
Never interrupt a questioner just because you know the answer. If you wait and carefully listen to the question you not only show common courtesy, you might find a clue to how to provide the best answer in the way the question is asked.
Hint no.2: Pause before answering
To help yourself to remember not to interrupt the questioner you should make it a habit to pause before answering any question. There is no better way to make the person who asked the question feel that the question is important and that it requires time for reflection - which most questions actually do.
Hint no.3: Answer the question when it is asked
"That's a good question, I will come back to that later" doesn't work. By telling the audience that you will answer "later" (when is "later"…?) you somehow tell the audience that what you have to say is more important than what they need to hear to follow what you are talking about. Of course you need to control your presentation structure, but in principle you should always answer a question when it is asked.
Hint no.4: Answer to the whole audience
For every question from someone in the audience you must assume that it is relevant to the whole audience. Consequently, you maintain eye contact with the questioner when he/she formulates the question but you then move to establish eye contact with the whole audience when you answer the question.
Hint no.5: Answer only the question that has been asked
Sometimes you can be temped to extend your answer to include many details and/or to move into related topics that you also know something about. Don't lose sight of the objective and structure (and the time constraints) of your presentation, so just answer the question that has been asked - no more, no less.