Keep track of the Trade shows you attend. Trade Shows that show a profit greater than the expense are the ones to continue attending.
Personnel that are selected to be your Booth staffers should have equal training before attending. These are the people that should be able to get qualified leads and most important should know how to finalize a sale.
Talk to your staffers and see what is working best for them and than suggest they all use the same approach.
Promotions are always a good way to go, a drawing at the end of the show which all must attend, but be sure the prize is worth the wait.
Promoting oneself with signature give a ways, pens, pads, shopping bags, literature, etc. Is always a good way to go.
With regards to your Exhibit design, try exhibit graphics that have fewer but bigger elements that emphasize your client’s benefits. Use bright colors that attract and designs that whisper “STOP HERE WE HAVE SO MUCH TO OFFER”.
And finally bring lots of products so all can see and feel what you are