Questions, not comments
The Q&A session can be a stressful part of any talk, so handle it carefully.
Make sure you have a chair on hand to ensure things go smoothly.
If I’m chairing a session that I expect will provoke strong opinions, I remind the audience before I pass around a microphone that the Q&A is for questions, not comments.
If somebody starts “This isn’t a question, but a comment”, cut them off. Move straight on to the next person.
People have mixed feelings about the Q&A. Some speakers find them very helpful; others prefer to answer questions in the hallway after the session. I’ve started to see CfPs that let speakers choose if they want a Q&A, and I think that’s a good compromise.