Mark all of your items clearly and be sure prices are easy to see.
Expect early birds and consider offers.
Be friendly and attentive (be ready to answer questions and be able to wrap breakables).
Have lots of change ready and someone to help you when you get busy.
Display your most interesting items at the entrance of your sale to draw passersby to your sale.
If something isn’t for sale, keep it away from your sale space or mark it as “Not For Sale”.