Ask how the image becomes an object
A photograph is more than a file. The print process, paper or substrate, ink chemistry, surface, border, mounting, and scale all affect how the work looks and ages.
Confirm whether the print is supplied loose, mounted, or framed, and whether the listed dimensions refer to the image, paper, or outside frame.
Edition size and future production
The artwork record should state the full edition size and identify the impression you are buying. Ask whether other sizes exist and whether those sizes belong to separate editions.
Signed open editions and one-time artist proofs are different from numbered limited editions. None is automatically the right choice, but the description should be unambiguous.