These are fun. I have done many, and they can sometimes be lucrative and other times not. It so much depends on the weather, who shows up and the phase of the moon (LOL). If you are doing table runners and home items, try to make them in prints for the season, ie brights and patriotic for summer, autumn prints in the fall, holiday later in the year. People do tend to buy what they can use right away as opposed to something to be stored for a while before using.
Ditto to the change, chair, lunch. I also have a cooler with water.
The advice on displaying items is right on point. Think of levels and separating items vertically so they can be seen. You never know what will catch a buyer's eye. Pegboards are great, and I use skirt hangers to display flat items.