I remember that some part of the gown needs to be safety pinned to the front of your top
I wore a dark shirt for my first graduation, and once I saw the photos wished I'd worn white, so that the gown would have been more visible.
Its seldom that I'd suggest a white shirt for anything, but this was an occasion when it would have been fitting,
Simple dark skirt, nude tights, good discrete shoes and a trip to the hairdressers.