Buy them cheaply at office supply stores or warehouse stores. Hang garments on the rack and cover the rack with an old sheet to prevent dust. If you must keep a spouse's old college textbooks, LPs, or childhood library, nothing beats small moving cartons intended for books. Small boxes keep books neater and are easier to lift than larger boxes. Buy these from U-Haul and save the extra pennies for a few more plastic storage containers.
Underbed containers are a good idea for adult bedrooms or older children's rooms.
Store seasonal linens, table linens or blanket conveniently under the bed. Take a brief inventory of your completed, corralled storage areas. Note storage areas and what they contain. Input the list into a computer and print a copy for reference. At summer's end, Inventory Control reminds you where to return those items.