Make it fun to visit. Meet the press. Your industry publications are always at these meetings, so talk up your organization to them. You might hand out press kits and hold a press conference to announce important new developments. Color, lights, working models, movement such as a demo video are good draws.
Lighting is really important.
Be sure your booth area is well lighted and friendly, even if you have to bring and set up the lights yourself. Offer a little something extra to draw people to your booth. Candy is always a great attraction, or really useful giveaways. Build your contact list. Having people leave a business card to register for a drawing or to receive additional literature or samples is one good way.