Ways to have Great Garage Sales

1. Realize it is all just stuff.  People are more important than stuff, and you don't have room in your life for people if you are always taking care of extra stuff.
2. Realize it's not really worth as much as you paid for it.  Marketers made you think it was worth that $300 you paid for it, but now that you've used the heck out of it for a few years, and you've farted and sneezed on it and didn't always wash your hands as well as you should have and sometimes spilled your drink and wiped it clean with a shirt tail rather than actual cleaning products.... not so much worth hardly anything.
3. Put up good signs.  It really does not matter what you write on your sign. People who shop garage sales don't slow down long enough to read your little sign.  Salers will see your neon arrow, and follow it, however.  The arrow, address, and day/time are all most people read on the sign.... I asked. 
4. Put up LOTS of signs.  At the main road at the entrance to your 'hood and at every major intersection inside your 'hood. You know which ones those are-- the ones that have the most traffic. 
5. Don't tape your sign to the stop sign.  It's annoying because usually the sign doesn't get taken down, either.  It's also usually illegal.  I recommend getting boxes and putting a weight in the bottom-- a big bag of rice or beans or a rock, whatever you have available.  The box doesn't blow over like a posterboard, it stands on its own without making a hole like a stake, and the rock generally holds it in place.  Plus it's 4 sided so at a 4-way you can have a sign facing all directions.  (Or use old Priority Mail boxes as your base, they are only 2 sided but tend to be effective IME.
6. TAKE YOUR SIGN DOWN WHEN YOU ARE DONE.  Yes, I'm yelling.  No one wants to look at your sign for another month. Go the extra mile and pick up your signs.  I actually like to keep my signs generic and re-use them for future garage sales.  A simple arrow with the address, FRI/SAT 8-1.  You really don't have to write "garage sale" because... well... DUH.