One quick comment about the most important thing you can do outside of the performance itself. Before you start, go around the room and introduce yourself and shake hands with everyone. After the performance....mingle with them and do the same thing...shake their hand and ask if they enjoyed the show.
Like Gary said, you'll get a lot of mileage out of using a hand sanitizer. BUT...what's important...until you use the hand cleaner...do NOT touch any opening in your face where germs could enter. Do that and you'll be fine!
But the truth is, as someone above said, there generally aren't any germs to begin with!
Lucky