When a framing job is complete, some form of packaging is needed to add the final touch. Customers will like the fact that you have taken the trouble to wrap their work neatly in a way that makes it easy for them to transport without risk of damage.
Many framers use Handywrap, especially on smaller frames. As it only sticks to itself, it will not damage delicate frame finishes. Wrap Handywrap several times right around the edge of the frame to give a measure of protection. Handywrap is also good for wrapping several frames of the same size together - face to face is usually best.
Bubblewrap is good too, especially for bigger pictures. Use several layers for extra protection, or use Bubblewrap to make up pads to cushion the vulnerable corners. These pads can be held in place with Handywrap.
Kraft paper is ideal if a tradional look is preferred. Although it is lightweight and strong (the name 'Kraft' actually comes from the German for 'strong') it is not really thick enough to give a large picture much protection. Use Bubblewrap for these, with Kraft paper as an outer cover if required.