Ad specialties are more and more popular, and they come in an endless variety. These are ad specialties aimed at true potential customers. These items are usually a bit more substantial, but you should purchase fewer. Unless a customer has immediate need for your business, most flyers end up in the trash. This is actually a good thing.
Some companies like to send out pre-show mailers inviting potential customers to their booth.
You establish your company's image through your booth design, graphics, and items on display, but it is the employees who will leave the biggest impression on potential customers. Make sure the people in your booth work well in pressure situations. At times you'll have hordes of people in a noisy environment. I am not a fan of chairs in a booth, but if you have them, use stools or director's chairs so you can quickly stand to talk to a customer. The break, by the way, should not be taken in the booth.