Here are the steps you need to take for a successful trade show:

Selecting the right show.
Ask lots questions of the people who are sponsoring the show. They are there to answer all your questions and encourage you to exhibit there. Are the exhibitors who are already registered appropriate for your products and services?
Pre-show preparation:
Mail or email something to your customers and potential customers to let them know you will be at the show and what booth number you will have. Also, follow up with emails. I suggest you produce literature for the show. Handouts that fit into #10 envelopes are great and you can include a mail out panel, which can be mailed to them after the show.
Your presentation at the show:
Perhaps you have an exhibit booth and a lot of show experience. That gives you a great advantage. If not, then you can either purchase or rent an exhibit booth. Get going on this well in advance of show time. Also, have the exhibit set up prior to the show so as to allow time for any necessary changes in time for the show. The message on your booth should be simple and straightforward. Remember, a trade show exhibit is similar to a web site in that you have to draw attention with impact quickly, or potential customers will move on. Are you offering something special at the show like a discounted price? What else besides a discount can you offer at the show that attracts people to your booth? At the end of the show take notes on what you did well and what you would do differently at the next show.
After the show:
This is very important. Contact potential customers as soon as you can when you return from the show. Also have a meeting right after the show to go over your notes from the show and plan what needs to be done when and differently for the next show. By doing this now, you are bound to maximize results at your next show.