I have only participated in exchanges organized by someone else (ie: schools, businesses, etc)...but here are some tips that may help. I always prefer to participate in things that seem more organized than "fly by the seat of your pants" ~ but that's just me.
I would decide on how you are allowing the swap. If you bring one plant are you able to take more than one "new" one? Maybe provide sometime of slip to hand out for every plant you bring (unless you really don't care, or don't want to be that "formal"). That just may cut the feelings of someone being slighted. Also, are people just jumping in and taking whatever, whenever ~ or are you wanting some kind of order to it?
I would also ask for slightly more information about the plant (if the have it). I would ask to have them include things like color, height, spread, preferred conditions and bloom time in addition to the common name. This way it may help others who are not familiar with one specific plant.
Other than that, I would sort the plants when they are brought so they are with like kinds.
I am sure that you will have a fantastic time, and most of these tips you won't need. Like I said, for my peace of mind I need to have a contingency for everything ( I HATE looking disorganized

). Good Luck on taking home lots of fun new plants for your yard!
