Paper should always be handled by diagonally opposite corners to prevent creases. When storing large paintings, it is easiest to set them on the floor. Keep them separated b foam blocks that are cut to fit over the top corners. This will make them accessible to show clients while keeping them safe, and demonstrate their value. Few things confuse studio visitors more than the contrast more than the contrast between the prices of artwork and an evident lack of care.
Shipping always poses a problem.
Using wooden crates built to specifications is the correct solution. Look in your local yellow pages for crate builders and art handlers, and compare prices. These are only a few highlights in a long list of suggestions, but they can help you plan ahead when arraging your studio and thinking of new work. Ultimately, it is the artist's responsibility that their work will look its best in the future. A manual for curators, collectors, conservators, artists and students.