Drawings for the public are prohibited in NJ. I had, at one time, a tri-fold display board with maps and community info. It worked quite well for visitors from out of the area. After several open houses, time took its toll on my display board and I have not recreated it. It was helpful to the public and generated interest with about 1/3 of attendees, which I considered very good.
Bottled water w/ labels, property brochures, community guides, sample listings of other similar properties (carefully distributed, as my first purpose for being there is to promote that property), CD's with Virtual Tours, agency disclosures explaining representation, balloons outside, balloons inside to give to kids.
I stay away from food or drinks other than water. My display board featured a county map, parks and recreation info, transporation schedules and pics for the ferry and train, a chart with mileage for frequently traveled routes (airport, NYC, etc.)
I do a walk through of the property to refresh my memory of the mechanical questions that may be posed throughout the day. i.e. location of electrical panel, amps, size of water heater, access to crawl, etc. Knowing these things on demand better promotes both the property. I make a quick round of minor tidying details, open the lights and a few closet doors.