I have implemented a new rule with my husband and kids. When ever they get something new THEY have to pick something old that they don't use or is broken, ect to get rid of. It keeps the house clutter free and saves so much time on toy clean up because they only have a few.
It will not work if you pick the item to get rid of they will look at it as a punishment rather than helping out. Let them pick the item that goes to the trash or good will.