Here are a few innovative sales techniques that the larger, more successful shows are using. Some may be appropriate for you.
Pay low, bonus high. Base salary (or draw) for salespeople is set at about one-third of total compensation (to illustrate, $40K base, $120K total compensation including bonus or commissions). This does wonders to focus the salesperson's attention on sales.
Don't commission renewals. Transfer responsibility for renewals to sales coordinators who are not commissioned. The salespeople only handle new sales (and upgrades). Exception: each bellwether exhibitor is assigned a salesperson to handhold them (and to work on increasing their participation).
Eliminate sales territories. Any prospect may be called on by any salesperson provided no other salesperson has documented a call to that prospect in the last 30 days. To do this, you must have a good contact management system that is used by all salespeople.
Don't sell to the exhibit manager. In most cases, the exhibit manager's job is to minimize the cost of the exhibitor's show participation (and not to maximize the sales return). Therefore, find and sell to those whose role is maximizing sales, such as the brand or product manager.