Prepare three to six engaging questions before the show.  Samples:

Establish an even gender balance in your booth

Set measurable goals before the show

Remember the 80/20 Rule... Listen 80% - Talk 20%

Minimize the use of trite questions (How are you?, etc.)

Avoid sitting, eating, and drinking in your booth

Be friendly and non-threatening

Smile

Ask open-ended questions - Beginning  with Who, What, Where, When, Why or How

Relate questions to the industry, product/service and its benefits

Never sit, read, eat, drink or talk on phone in your booth

Never close off conversation by crossing your arms

Never stand with your back to the aisle

Don’t say "Can I help you?"

Never drink alcohol or eat garlicky or spicy foods during the day

Never badmouth your competitors