Look like a "10"

 The #1 visual in your presentation is you.  I know it’s hard to believe that you’re more important than that Microsoft Powerpoint presentation you spent hours creating.  That’s why your appearance matters.  Consider your audience.  In what geograpy are you speaking?  Are you speaking on the West Coast or the East Coast?  Are you speaking at an event at the beach or at a black tie affair?  The clothing style and expectations are different based on geography, time of day and event.  Ask yourself, what would the audience expect me to wear?  Ask the event coordinator how the participants will be dressed, then dress one step above that level.