I've spent a lot of time in front of people showing, teaching, and helping people do things. I did a little showing this weekend. The 4 things below will help no matter what type of demonstration you do. 

     • Do it large         
          Large scale helps with large crowds - people could see my painting 50 yards away & could watch all day      
     • Engage Others
          Create an exchange with others - I let some children paint on the painting, fun and different for those families
     • Make it easy
          This isn't the time to experiment - I could do this type of painting without thinking
     • Open up
          Something like this is as more about meeting and talking with people than it is painting