I usually do really, really well at my yardsales ($600-$1000). I always do them during the neighborhood sales....more traffic = more money
-Have everything off the ground. Tables, boxes flipped over, ect.
-Display clothes on chains. 1 hanger per link. That way the clothes don't bunch together.
-Price everything in .25 increments if possible.
-Have a junk box marked FREE or .05. This is great to draw the kids in.
-For things like books or stuffed animals do a .25 each or 3 for .50 type promotion
-Sell drinks. We always have water and soda in our garage fridge so we sell that at .50 a bottle. It really adds up. I am not out any extra money since we always keep it on hand anyway.
-Keep your money on you at all times. Keep all change inside the house and take all large bills in at regular intervals. Helps to have a partner to run in and out of the house for you.
-Make sure all doors to your house are locked except for the door you are closest too. Be aware if someone is trying to distract you.
-Do not hold items unless they are already paid for and are coming back to pick up. If you do decide to hold an item, give a set time (say 1 hour) and then put it back out to sell.
-If the sale starts at 7 am have your stuff ready to go at 6am. Buyers will be out early, especially if there are multiple sales that weekend.