Design
Text
Text needs to be well thought-out and concise. Keep it to a minimum: all you should be doing is providing a taster for the visitor. Your salesman or sales literature will fill in the details. Do make certain that it is large enough to be read.
Think about what is on your stand (people, furniture etc.) and plan your content around the space that will be visible most of the time.
Who will be reading it? - Very technical subjects will lean towards more in depth content. As a general rule, keep it concise and punchy; most people won't stand and read it but you have an opportunity to raise your company's profile so make sure your most important message can be read in a few seconds as attendees walk past.