How do you ship headphones and gear?

Hey guys - question regarding shipping expensive headphones and gear.

I shipped a package UPS ground earlier today, insured and it seemed I may have overpaid. Any tips on the best way to ship a set of expensive headphones, w/ insurance?

Any good tips on ways to save money on shipping costs? Also, how do you ship differently depending on weight and size of the item, and insurance requirements? Are some postal carriers better for heavier items vs smaller items? Standard box sizes that ship cheaper?