Learn to pay attention to the details that will help you attract the types of audiences you'd like to speak to in the future and what you need to do ahead of time to make sure you look, feel and sound your best on stage including:

Who is in the audience
Where you are in the room 
What you will wear

With a little planning and some homework, you can make sure your audience focuses on you and not what you are wearing.

References:

Nick Morgan

Study - Psychology of Objectification

Rando Martins

Resources:

CR 5 -  What to Never, Ever Wear on Camera... pdf

CR 6  - Are You Ready For Your Close Up? pdf