First, find a place with good lighting to take reference photos or a video of your art. Outside on an overcast day is good.
Stand your art against the side of a building and record the image very closely cropped.
If you are video taping, announce the name of the artwork, the date it was created and what medium it was made with. If you are taking photos, make detailed notes in the order that you take the shots.
Save the video or photos, with the notes, in a safe place. Let your power of attorney know where you have put the catalog.