It can be a lot of work, but you can unload some of your clutter and make some money for future garage sale shopping. Think about the ads that drew your eye. That's the type of advertising you want to use. Provide directions to your sale. Include times, dates, address, and list some items for sale or reasons for customers to seek you out.
Street signs are a real help.
Write the letters large and use contrasting colors. Black on white or black on yellow are easier to read than other combinations, such as black on brown cardboard or pastels on white. Use few words. Drivers don't have time to safely read a list of items, addresses, dates and times. Put signs at each of the corners on the way to the location.