What's the Homemaking September ShapeUp! all about?
You've been collecting items all month long in a Sell/Donate bin, or perhaps multiple bins. Now is the time to address these bins. Make a plan now. You don't want to find yourself storing stuff you no longer want. It's counterproductive. Space is valuable, why waste it.
If you have any higher dollar items that you want to sell, I would suggest e-bay. At garage sales all you can do is hope that the right buyer hits your sale that day. If you want you can use e-bay to determine what it will probably sell for, then put it on your garage sale for that price. If it doesn't sell, then put it on e-bay. It's worth selling an item at a slightly lower price at a garage sale to avoid the hassles of writing a description, taking pictures, listing it and shipping it.
For items that you are going to donate, make sure they are in good shape and clean. Call your favorite local charity that takes donations and find out what items they accept. Everything else can be given away via freecycle.
Get it all out of the house, you don't want to store it, or dust it, or have to look at it again in 3 months when you can't remember what's in there.