Choose a place with fewer swings
The Smithsonian Institution Archives describes stable temperature and relative humidity as important for collections, and notes that light can fade or chemically alter paper, leather and photographs. Its guidance also cautions against attics, basements, garages, exterior walls and windows. Keep the storage place stable and away from direct light.
Let the object guide the enclosure
The National Postal Museum describes sleeves made from polyester or polypropylene for documents, while also advising that a sleeve be slightly larger than the item and that only one document be placed in each sleeve. Fit and condition matter, so do not assume every material or album suits every object.
Avoid a forced fit
Keep pieces flat and supported. If an item is folded, brittle, stuck to another surface or otherwise unstable, ask a conservator before flattening, separating or mounting it.
This guide is general information, not conservation or legal advice. Check the guidance and rights statement for the specific object you are handling or sharing.