Given the relative values of artwork and packing materials, it makes sense to err on the side of caution when shipping art. Your control over the work of art ends as soon as it leaves your hands, so you need to plan for the worst when packing and save yourself the disappointment of a damaged work. For extremely valuable works of art, you can hire the services of professionals that have experience in this field.
Protect the front and back surfaces of the paper with tissue paper. Fold the tissue paper around the print and then tape it together. Be sure to tape the tissue paper only to itself, not to the print.
Lay the print flat on a piece of sturdy cardboard that is four inches wider and longer than the print, leaving a two inch margin on each side. Lay another piece of cardboard the same size over the top, sandwiching the print between them, and tape them together securely.
Secure tape around all the edges where the two pieces of cardboard meet. For added security, you can put two or even three pieces of cardboard above and below the print to insure that it doesn't bend.
Apply a "Fragile" sticker or write "Fragile: Do Not Bend" on the cardboard in bold letters.