Clean and repair jewelry.
Organize jewelry by type.
Since all deficiencies are noted in the appraisal document, (broken prongs or missing stones, for example) repair or restring items prior to the appointment.
For example, if you are a collector, sort by designer, period, famous maker, or category, like all bracelets, all rings, etc.,
Certificates from GIA, EGL, AGS
Old insurance summaries
Jewelry history/photographs are helpful with family pieces and assist with documenting provenance (history of ownership)