Find out what the show is about. Plan your demonstrations according to the expected type of crowd. Do not attempt to demonstrate firewalling to someone who barely knows anything about networking.
Get organized quickly. This means you should be ready at least a month in advance. Getting organized early will leave you spare time to plan your demonstrations.
Try to reach a deal with one of the Linux support companies—get a full or partial sponsorship, and some agreement for returning unsold Linux items.
Set up a mailing list and a web site if you haven't already. Distribute these addresses on flyers in the show—lots of people will want to get in touch with you.
Foster an enthusiastic spirit. One of the reasons our booth did well was that our people were mostly young, enthusiastic students trying to inspire others, rather than boring, trained salesmen just doing a job.