1.  Start Early.  Put things in a designated area for the upcoming sale.
2.  Price Everything.  Use masking tape or labels, and group items by price points for fast and easy pricing.  (Ex. $1.00 table) Or you could buy pre-printed tags (Ex. $.25, $50), so you just peel and stick!
3.  Have a Change Fund.  A total of $10.00 in coins and small bills should be plenty.
4.  Get the Children Involved! Consider letting them get involved, by selling sodas or lemonade.  They can also set up their own table of toys for a little entrepreneur endeavor!
5.  Save Grocery Bags, for people who purchase multiple items.
6.  Display items, on card tables, Ping-Pong tables, or patio tables.
7.  At the End of the Sale, donate any of the remaining items to charity.