DRESS TO IMPRESS
Decide how you want your team dressed - what are they going to be wearing? Branded clothes will help visitors easily and quickly identify whom they should be speaking to. Also, if your staff are walking around, then they are obviously more visible and gives you that little bit more brand recall...
Costumes are great IF they are relevant to your story, and IF the costumes are good quality, and do not give off the vibe of having been hastily procured at the local party shop.
I know these are obvious but worth mentioning never the less: make sure your team are NOT over made up, are not wearing strong perfume or aftershave, do no gossip, do not eat or drink at the stand. Make sure they are well rested, alert, take breaks, drink plenty of water, are wearing comfortable shoes and have a spare set of clothes and shoes.