There are tons of approaches to a bridal show and part of it depends on your specific market. Here's how we approach it for our market and it works very well for us.
We bring a basic system to play music on, so mixer, amp, speakers, etc. We purposely select music that is more upbeat and fun...we stay away from slow lovey songs because several other companies do that music and it does not convey energy and fun. We only bring two of our lights, the Chauvet Eclipse and Cirrus, they are pointed at the ceiling (it's a higher ceiling) and they attract attention to us (for 3 straight years now). We've got business cards that match the brochures. Our photo albums are out with snapshots from different events we have done. There are no pics where you can easily tell who it is and any minors have had their faces blurred. We always have a bowl with Lifesavers Wint-O-Green mints that sits next to one of our business card holders. This bowl is kept near the front so that anyone walking by can grab a mint and a card.
As for give-aways/free drawings. This past year we gave away a Vermont Teddy Bear each day. In order for a person to sign up for it, they actually had to talk to us (this helped avoid the ones only looking for freebies) and only the bride and groom could enter, the mother of the bride couldn't do it for her daughter, etc, it had to be the bride or groom.
In regards to booking at the show, I'll disagree with Houston. Our entire model is designed to get the couple to sit down with us at a future meeting to discuss their specific reception (we're at about a 93% rate of meeting to booking). We always have contracts on hand at the shows because some people will want to book on the spot and we'll never turn then down at that point (we've had at least one on the spot booking each year).
How much to pay for a booth at a show, it depends on your area. For our main show we pay almost $700, but that's for 10 hours of show over two days. Our smaller show is $225 for one day and many of the other shows around here run about the same.