|Many of these are very popular nowadays. Some collectors opt to proudly display their coins in archival folders, while others prefer air-tight capsules, or mylar-lined 2x2's. Whatever you choose, do not store yours in the PVC flips you often see on the market. They are comprised of PVC which decomposes over time and destroys the coin it was intended to protect. In the event you purchase coins already within such a sleeve, move it as soon as possible to something better. You may consider acetate flips, but recognize that they are brittle and may scuff the piece if it is not placed and removed with care. While they aren't airtight, they are adequate choices for medium value coins that will be "left alone" for numerous a long time.
One thing is for sure: regardless of where you choose to keep your coins, it'll always a source of permanent pride.