Make a clear table
The Smithsonian National Postal Museum recommends working on a clean, flat surface and keeping food and drink away from letters and documents. Give each piece a little room before you begin.
Keep handling simple
Clean, dry hands and an unhurried pace help avoid accidental pressure, snags and marks. If an item is fragile, valuable or already damaged, pause and seek conservation guidance instead of trying a repair at home.
Leave the original unmarked
For notes, the museum suggests pencil in a discreet place and cautions against fasteners such as paper clips, staples, rubber bands and sticky notes. Store related envelopes with their letters when they may hold useful context.
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.