The Internet has allowed information to be at the the fingertip of anyone wanting it. This also works with garage sales. Below are a few resources that can be used to help get the word out about your garage sale. They allow free listings and are separated by state. These sites work great as well for finding some otherwise unknown garage sales that may be in your area.
There are deals to be found in any neighborhood but to optimize the chances of scoring a big find, you need to be aware on where to look. The easiest way to explain the difference between communities is simply by their financial status. Lower class, middle class and upper class each have garage sales but they many differences as well.
This group of people is the most likely to have garage sales often. In my experience they tend to resell a lot of their items, meaning they too go garage sale hunting and turn around and sell it soon after. I have seen many times a house that may have multiple bikes, highchairs and even strollers. Unless you are looking for a specific item that you believe would predominately be purchased by a lower class citizen, then I would recommend driving passed these houses. They are normally a waste of your time and don't have things that you want
This is by far the best class you want to target. They commonly have clean items that sell for a good price. They tend to be having a garage sale to help clear out room in their house rather than to pay the bills. They can often be bartered quite well and you can find some great finds in general.
I would say that the upper class simply has the fewest garage sales. This may be for the good since they often try to sell their items for way too much. It is often that you will see one of these houses selling a used item for near the same price as new. Business savvy people tend to live in these neighborhoods which will bleed over to their garage sale where they will attempt to make the sale benefit them more than the customer. You may find a good deal every once in a while but commonly, these should be passed by and viewed quickly.