I participate in 1 large show each year. I have had really good success at this show.
The main thing is you have to stand out from the other bakeries. Make sure your dummy cakes are stylish, up to date and have several different designs/color. I have 1 all white, 1 ivory, 1 bright yellow with red flowers and 1 black and white with a pop of green for color. All my cakes have sugar flowers on them.
Also, pass out mini cupcake samples that will stand out (not just chocolate and yellow cake). At the show I just did there was a bakery passing out full size cupcakes. I was around the corner from them, so the trash can at my booth was the closest trash can that was out of sight from the people with the big cupcakes. So many brides were throwing the cupcakes away saying the servings were too big since they wanted to try everything at the show. Bite size works best.