Mouth
Obviously, it’s important to brush and floss your teeth before going in front of an audience (unless, of course, you’re expected to speak directly after a meal and you’re unable to excuse yourself for a quick stop to the lavatory.)
Some speechmakers even carry mints and mouthwash for an extra level of fresh breath confidence; however, never give a speech with anything in your mouth such as gum or mints. (A cough drop is fine if you’re truly ill, but do explain its presence and make apologies for its presence at the start of your speech.)