I recently had a garage sale and this one made the one most money out of all of my garage sales. Why? Because I had 3 other people add their items to my garage sale and because we had a neighborhood garage sale where other neighbors participated. Well that's at least what I attribute my recent success too.
I also let my daughter have her own bake sale where she sold out of all of her items and and had people asking for more. I think it is important for them to have a role in the garage sale as well. She loved it!