Nice, exactly what Cedars said.
Make sure your placards are large and tall though so if attendants come out to block the
signs you would be able to reach over them, so people could still see them.
It wouldn't be prudent to talk to JWS or verbally confrontational, just make a brief
statement such " please do some research " and keep walking.
Oh yes and never go on private property such the area surrounding the convention site,
always stay on public owned land such as side walks, where its legal to protest by law.
Your work just may Awake some people to rethink what they're involved in.