I know there are people that plan their shopping ahead of time - but I am one usually 'follows the arrows'
* Have your signs LEGIBLE from a distance - In fact, have a BIG arrow - with the point really big - at the top of the sign. I have trouble seeing/reading signs from a distance. (Although my DH who can spot an airplane at 5000 feet NEVER seems to be able to even SEE a garage sale sign!) An address is okay to put on the sign, but it's not the first thing I want to see.
I usually am unfamiliar with the area that I'm in - so an address is totally meaningless to me. And a two inch arrow at the very bottom of a cluttered sign with half-inch high pointer is worthless. By the time I figured out where I should have gone - I've missed the intersection, or I'm in the wrong lane.
* I like the idea of a given sale having the 'same' signs all the way to the sale stage.
* If your location is in a place with a lot of y-streets - arrows pointing the way are very helpful.
* Put a clear plastic bag over the sign if it's been rainy. Also, try to use two posts so that the wind won't blow it away or twist the sign.
* I have heard of people taking signs down - so if you can - check on your signs once in a while to make sure they are still there.
* Have your stuff clean and displayed neatly. Unless you are willing to let the stuff go very cheaply. I am willing to pay more for clean stuff than dirty stuff.
* Have things marked. If you are planning to have a drastic reduction on the last day, perhaps a sign indicating that would be helpful.
* If you are going to allow early birds to shop - maybe charge them more? I feel cheated when the ad says the hours are 8 - 4, I get there at 7:30 and I see people leaving the sale with bags and bags in their hands.
* It's also helpful to have similar things grouped together - craft stuff together, puzzles/games together, etc.
* If possible, have clothes hanging up - and not overly crowded. It's more fun to look if I can actually see the garment without several of them coming out with the one I want to see. It will also mean less refolding of garments for the seller!
*Try not to have things where people will trip over them or hit their heads on them.
* Acknowledge a potential buyer when he/she shows up.
*Take the signs down when the sale is over! PLEASE PLEASE PLEASE.