I think I have missed the window, but for future reference this is what I do/have done.
I started out with a foamboard like kids use at science fairs. I created a display with my photo, brief bio, and sample materials. I had brochures, business cards, pencils, pens, and keyfobs for people to take. I used an inexpensive, white sheet to cover the table.
I have since "graduated" to a real display board which is hook-and-loop friendly.
I have my company name and Web address, information on services, and a copy of the ad I have been running in a local business weekly. You will also see (if the photo link works) I have some plastic display frames (purchased at a mega discount outlet) with a brochure, bio, and announcement of my upcoming book. I purchased 2 acryllic brochure displays, business card holder in a clearance rack at an office supply store.
The Ukeep binder in the middle holds copies of letters, articiles I've written, and sample documents I've created. They are in page protectors so interested individuals can review or I can show them as I speak to someone.
I still place pens and keyfobs for people to take. They have my company name and Web address on them.
Even at a tradeshow, you need to get out and approach other vendors. I suggest taking someone with you who can "man" your table while you are mingling. Or, have enough info on the table that you are comfortable leaving it unattended.
Good luck!