Whats the cheapest way for me to ship?

-I want to start selling things on ebay but the only thing thats holding me back is how to ship. I am going to sell bottlecap necklaces, i dont know hom much it weighs but its not much. (a bottlecap and a necklace chain.) I want to know what the easiest way for me to ship it. whats the differences in Express, Prepaid, Priority, International, First class, Regional rates. i know it would be easiest to go with flat rate but i think if i choose one of the others it will cost almost half the price. And when im shipping it do i need to have it sent in a bubblewrap envelope? or is a regular letter totally out of the question? Pleaseee hellppp