My mom lives a long way away - too far for me to help - and started to organize a garage sale after the death of her longtime partner. When it became overwhelming she found a man who likes to sell things at flea markets and auctions. The man loaded up everything for me, took it all away to sell and they split the money. It's possible she could have made a little more money, but for her getting rid of everything without the hassle and labor of a garage sale was more than worth the price.
A big thing to remember, yard sale chasers show up way ahead of time, so be prepared. We've had 8-10 sales in the last dozen years and each time, even when we had our newspaper ad state, "no earlybirds," before the specificed starting time, they still show up. We had a 6 a.m. sale once, so we got up at 4:30 to get showers and breakfast out of the way before setting up. We opened our garage door from inside about five minutes after five to get things set up and as it opens, we see two cars parked in front of our house and four people sitting in them waiting on us. Just be prepared for this, you might set up the night before if you have a fence around your yard. I'm really not sure any other way around this, because we haven't found one.
Maybe I'll chain my neighbor's dog in my front yard to ward off earlybirds. Ehhhh, prolly not. He'd just lick 'em to death.