A great web for presentation:
At all times: courteous, gracious, & professional
When audience members ask questions or give comments, you should be gracious and thank them for their input. Even if someone is being difficult, you must keep to the high ground and at all times be a gentleman or lady and courteously deal with such individuals. The true professional can always remain cool and in control. Remember, it is your reputation, so always remain gracious even with the most challenging of audiences.