Got an extra hamper lying around not collecting anything. To make clothing donations super easy and contain the clutter...consider keeping a large hamper in each closet to collect clothes that don't fit anymore. If space is limited, consider keeping a hamper in one central utility closet or room.
Here's a great tip for people who are often on the road. If you have the room in the trunk of your car, you can also keep a bag, box, or small hamper in the trunk to house items you would like to donate to charity. Whenever you find something you don't need anymore, throw it in the trunk. That way you make it easy to just drop it off at Goodwill if you happen to be driving through the area. This is one way to save on gas by combining your errands.