I totally support the suggestion about pre-marketing.
Find the Trade show's hashtag and if it's a business show (particularly one that repeats annually) create a Linked In group for the whole show.
Research and create content which is being produced by the organisers, speakers and other exhibitors and publish it to two places - your blog and the Linked In Group.
Using this curated content strategy, you will be the place folks come to read more about the event, plus you get the chance to arrange meetings in advance with key attendees.