It's overwhelming to start sorting through your belongings when preparing for a garage sale. To keep from becoming beleaguered by the sheer vastness of your things, you may want to implement some sort of system to keep things moving or at least in place. The following is a sample organization system -- just one; there are a ton out there you could use, and of course you'll want to make your own that fits what you're doing -- that can help you keep your garage sale hosting life in order.
Note that this system (and others like it) are especially useful when you're rearranging your entire home -- perhaps switching rooms' residents, or filling the spare bedroom when one of your children goes off to college -- or when you're moving. It can work for when you're doing a smaller-scale purge of your belongings, as well, but it might be a little drastic for less intense purposes! Use it with caution.
Sort everything into three piles: keep, garage sale, and donate. The keep piles can be kept in the most inconvenient places, where you won't be able to reach them until you've gotten rid of all the other piles. The donation pile should be in front, and this is where items you're positive you can't sell will go. In between these two can be the garage sale piles -- things you don't want any more but think you could probably get some money for.
Keep everything separate as much as possible. This may require the use of bags and boxes, to be certain your piles won't accidentally mingle and merge. After all, that's how you can lose items you were positive you didn't put in the donation or garage sale pile! For things like toys or little trinkets, you could have difficulty creating actual piles, and will want to utilize containers to avoid mixing them up.
Price as you go. If you have a good idea of what your pricing system will look like before you even get started on your possession purging, you can keep your pricing stickers or roll of masking tape with you and price as you go. This will eliminate the entire step of sorting back through everything and putting on the pricing stickers.
Your next step should be pretty clear -- come visit our home page, GarageSaleCow.com, and list your garage sale for free today!