Picking up a paper artwork between your fingers will cause it to cockle (especially photographs and glossy posters).
Always handle on a firm carrier board.
Take care with pastel and charcoal images they are easily smudged. ‘Fixing’ with a spray fixative offers limited protection.
Use of pressure (self adhesive) tapes is not recommended adjacent to artwork. The adhesive will migrate into the artwork causing discolouration and the tape eventually fails when it dries out. Much better to use a water solvent adhesive such as gummed tape.
Artwork that has tangible value should be kept in it’s original condition to maintain value. It should not be cut or trimmed, nor should it be bonded with an irreversible adhesive.