Since you have already priced your items this is one major step you have completed. Keep your pets out of the way, for their safety and the courtesy of your shoppers. Set your sale up carefully with items grouped together, marked with prices, clean and attractively displayed. You'll have more success. It's better than a tarp on the ground.
Items are easier to see.
Have an extension cord ready to test appliances and lamps for your customers. On hot days your customers will thank you and it also teaches kids the value of work and a dollar. Avoids problems later. Be friendly, be enthusiastic and have fun. Your attitude and enthusiasm will show.