Some items cannot be shipped because of law regulations. Inform yourself for such items before packing, in order to avoid furter complications. Hazardous matarials, flammables, acids, and all the items of perishable nature.
Listed below are the most common of them
Flamable, explosive, corrosive materials
Charcoal Lighter Fluid
Nail Polish Remover
Items of perishable nature
Opened Food Products
And remember, always take the valuable items and the items of personal importance with you.