I believe Mouthy did the best demonstration. No yellings etc, etc. Just stay quite with a board hanging over you with a brief message. This is the best way to do it.
It will be nice to have small messages on the board to make Jw's "think" a little bit, like:
587 B.C the real date of Jerusalims destruction
607 B.C came out from Russells influence by Pyramidology
Why did the Organization forbit Organ Transplants for 16 years?
Will Sodomah and Gomorah reserrect at God's Kingdom?