Polypropylene Bags : This is the most common kind of comic book bag. These bags are acid-free to make them safe for long term storage.
Comics have been published in different sizes through the years. Take care you buy the right-sized bag.
These bags are for current or modern comics
These are bags for Silver Age comics :
Bags for Golden Age comics
There are some comics like Savage Sword of Conan that come in magazine sizes, these are the bags for those
These polypropelene bags are resealable
Mylar : These bags are several times stronger than polyethylene and a bit more expensive. Unlike the flexible polypropelene, mylar comes across as a rigid, transparent film. Ideal for your more valuable pieces. You'll note that there are differences in mil size or thickness.
These are combo offerings with both bags and backing boards
For the beginner here's a starter kit
Backing boards keep your comics straight and flat even when they're upright. Boards differs in volume and size. These boards are archival and one side is smooth coated.
"Bag, board and box" is a common term among collectors. Here are the boxes - the long and short of them.
For easy identification and organization, dividers are used in a box to mark when one set of comics ends and another begins.
Display cases are for showing the prizes of your collection
Instead of using boxes other collectors use magazine files instead. Bagged and boarded comics stand upright in these containers which are usually put up on shelves for easy access.
For graphic novels and trade collections here are some bookcases for your consideration. Comics stored in magazine files can be stored here too.
My trades are usually safe on the shelf as they are but when I take them out on roadtrips they can get pretty bit up. Here are some items that can give your books some extra protection