Found this article on the BtoB News Magazine written by Karen J. Bannan. She writes "Trade shows have always been a great source of new leads; but, considering travel costs, booth construction, booth rental and collateral printing, they are also one of the most expensive" and she recommends following up via EMAIL.

This is a GREAT start to following up on those leads...but it really starts BEFORE the event and identifying your strategic objectives and who is your ideal prospect.  Then I would say you should contact via the phone your primary or "hot" leads and then email the rest to warm them through your sales process.

Trade shows should be an integral part of your overall marketing strategy - but just because you exhibit - does not mean 100% closed deals.  You need to work through the sales cycle just like in any other opportunity.