Be sure to get permission from property owners first, and avoid nailing signs to utility poles and trees. If rain is forecasted, cover them with clear contact paper. And road test the signs for readability. Chances are if you can't read them neither can the potential shopper in the car behind you. On the day of the sale, place large directional arrows along the route to guide shoppers from major intersections to your door or block.
Helium balloons get attention and add to the fun.
Organizing the sale. Borrow card or ping pong tables and arrange them so shoppers have enough room to browse. Run a long, heavy-duty extension cord to test electrical appliances. You can take advantage of the space under the tables by displaying large items and children's toys. These will appeal to young shoppers at just the right eye level.