If you are sending work to galleries/museums for exhibition or sale you may wish to follow these suggestion from the Uni of Delaware
WHAT TO INCLUDE ON THE BACK OF YOUR ARTWORK
Artists are highly encouraged to consider documenting their materials and techniques on the reverse of their artworks. Such information can be included in the form of a encapsulated or sealed label (adhered to the stretcher bar, panel support, or backingboard), a clear plastic envelope sheet (adhered to the panel support or backingboard), or even a simple hand-written inscription. Ideally this information should accompany the painting throughout its lifetime and will help to better inform researchers, conservators, art handlers, and other potentially interested parties. If you are using paper ensure that it is acid-free and that any inks used are fairly lightfast. If artists choose to use a pencil, it should leave a legible mark and not be easily smudged. While sharpie markers are often a popular choice, they can fade over time if they are exposed to light. Hand-written inscriptions on rigid supports can also be sealed with a protective varnish coating to provide additional protection. Artists should consider including the following:
Name and contact information of artist (phone number, website, email, etc.)
Title and dimensions of painting (HxW)
Date completed (and started if possible)
All materials used, including manufacturers information:
o Support, ground, medium, colors/pigments, etc. and associated brands if known
o Relevant varnish information as well as the date varnished if known
For insurance, tax and police information I recommend that a photo of this panel, along with the image of the painting be stored on a computer database. A back up should be stored off site in the cloud, or parents house.
Primarily this is a digital record of your studio work, but will keep track of sales contact info, style change over the years, pricing history, profitability, costs, loans, gifts etc.