You can keep them in the box they came in, or wrap them in a scarf or readingcloth if you have one. Or put them in any little bag of a fitting size, or hold them together with a soft rubber band (scrunchie or similar) that will not add unnecessary wear and tare to the edges, or leave them in a pile somewhere.
You can use any material you want in the pouch if you choose to make or buy one, and keep it in any kind of box you prefer. Even a ziplockbag will do..
The "rules" on how you "should" treat and keep your deck are not set in stone, and the most important thing is that you keep, use and store your deck in a way that suits you and makes you feel comfortable.
Most people keep their decks in pouches to protect them from bumps when they carry them with them in a bag with other things, or just for decoration because they want to give the deck a nice looking "home".
The only thing I want to recommend is that you find a way to store your deck that keeps it from getting discolored or damaged so basically, keep it in a dry place and try to not wrap or place it in anything that will cause discoloration or other damage.