When looking at how to ship a painting or other artwork, it's important to:
Determine the materials used to create the artwork, considering size and weight.
Choose the packaging based on what the artwork is; i.e. tubes for rolled up art prints or paintings that are on a canvas that can be rolled.
If there is glass or other fragile materials, protect them with padding or bubble wrap.
Use custom boxes for specialty artwork with obscure dimensions or special needs.