Press one piece of masking tape onto the mirror diagonally, from the top left-hand corner to the bottom right-hand corner. Press another piece of masking tape across the first to form an “X.” In case the mirror does break, despite your precautions, the masking tape will hold the glass in place.
Wrap the mirror in a thick layer of bubble wrap to cushion it. Tape the bubble wrap so that it stays closed.
Add a layer of crumpled newspaper to the bottom of a mirror box. If you don't have the mirror's original box, ask your moving company to provide a box especially for mirrors.
Slide the wrapped mirror carefully into the mirror box.
Fill any remaining empty space with more crumpled newspaper or packing peanuts.
Seal the box tightly with packing tape.
Stand the box on its edge. Never lay a mirror box flat to prevent warping or possibly stepping on it.
Write on the side of the box with a marker. Draw an arrow pointed up to the edge of the mirror box and write “This side up.” Also add “Mirror -- Fragile” in large letters so that the movers are aware of the contents.