If you are going to have your own sale, you need to plan ahead and know what you are doing. First of all, remember that many of the people will be driving by and you need to give them a reason to park their car and get out of it. The best way to do that is to have tons of stuff for sale and have it all CLEARLY visible. Look at the picture below. Now that is a garage sale that has some action and lots of stuff making people WANT to get out of their cars and look.
One of the worst things you can do is have a sale where everything is inside your garage. If you do that, you will see that many people in their cars slow down and then drive away after they decide it is not worth the effort. See the sale in the picture below? BORING and not worth the effort to even walk up the driveway!
Signs advertising your garage sale are also very important and shouldn't be underestimated. Too many people get lazy with their signs and end up assuming people will just stop by. But how will they know to come if you don't advertise? If you are going to spend half or more of your day hanging out at your sale, you might as well do the upfront work of making signs that are sturdy and do a good job of pointing the way to your house. Your cash register will thank you too.
Some people take the time to price every or most items while others don't price anything. There is not a right or wrong way but it makes sense to at least price the bigger items. The little things that are going to go for a quarter or a dollar don't matter but usually you have at least a handful of bigger ticket items you are trying to get rid of. Thinking what you want for them ahead of time and putting a price on them will at least give your customers a starting point for negotiation. Remember, just because you have a price tag on things doesn't mean you have to sell them for that.
A lot of people have garage sales to have fun, get rid of some junk, and to make a little money on the side. But done right, you can have a whole lot more fun than you ever thought if you have lots of things to sell and a constant stream of people with money looking through your treasures!