It is important to remove as many visual and auditory distractions for the audience as possible before you begin.
A quick trip to the restroom is in order to check that:
You have nothing stuck in your teeth
Your hair is reasonably under control
Any makeup is cleanly and tastefully applied. Yves Saint Laurent is reported to have said, "The most beautiful makeup of a woman is passion." I think that is true for all genders.
Glasses, if you wear them, are clean
No undergarments are showing, collar and pocket flaps are laying down, etc.
An orderly personal appearance reinforces an orderly presentation.
Have some business cards with you.
Put your mobile phone on mute or airplane mode!
You look great. Now go out there and knock them dead.