One way to effect the Value of a copy is personalizing it such as writing on the copy "To my best friend...", as this often devalues the copy. If you are giving the copy as a gift, it is best to write a personal note with the copy, and then the note could be a form of Provenance for the copy and/or it could provide an interesting history or touching story behind the copy for future owners. In short, leave the copy as is unless you can get a personal autograph from the artist. Storing the copy matters, in this day of information, there are a few online sources to top up your knowledge on the particulars of storing your copy,  generally a frame is best.