Not a big garage sale person, but I will add....

I don't care what they do with the stuff....just glad it's gone.

Set a start time and stick with it.
Charge an early admission fee if they try to crash the party earlier than the advertised opening.

Don't waste time pondering the perfect tagged price for something.
Pad it some because they're going to try to work you down anyway.

Get ready for some haggling when you have someone cherry-picking and making a big pile of their chosen stuff.

The biggest pain are the early show ups and the hardcore hagglers.
They take the fun out of it.