Very carefully.  For unframed paintings, they are packed either in a hard envelope or cylinder tube.  If in a tube, it will be wrapped with padding and strong packaging tape.  All packages will be double checked for stability and protection before leaving our hands.  We put fragile stamps on most packages.  In the case of our few framed or stretched artworks, they will be professionally packed by UPS or Fed Ex in a protective art box.  We bill you a non-profit quote for packaging and shipping via UPS for paintings with a frame.