Keep a bin, basket or box in a child's closet and one by the front door. As things become too small for the child, place them in the box if they will become hand-me-downs for the next child. When full, toss the clothes in a quality plastic kitchen garbage bag, mark what size and season and toss in the attic. They'll be fine for 3 years, I've tested it! If they are to be donated or consigned, place them in the basket by the front door. When the basket is full, put it in your car and make a trip to your favorite charity.