To store cryptocurrency safely, a hardware wallet is what all of the experts recommend.One of the things to remember is to follow the rules of the Self Directed/checkbook IRA. All funds and transactions have to be kept separated from any other transactions. That means, even though you may have multiple cryptocurrencies, the ones associated and purchased with your checkbook IRA need to be moved from whatever exchange you brought them from and placed on a wallet separate from any other holdings. The most famous and popular hardware wallet is the Ledger Nano S and the Ledger Nano X. The Nano S is the original version, and the Ledger Nano X is the Bluetooth version. With the Ledger Nano X, you can use your mobile device to transfer your cryptocurrency. I use the Nano S, mainly because the Nano X wasn’t available when I needed the wallet. The Ledger live software, is both PC and mobile based and is how you interact with your assets on the device. One item to take note is that you can only have 1 version of the Ledger Live software on a PC, but, you can have multiple accounts on the install of the ledger live. The label of each account can be changes, to make the different assets easily identifiable. Once your cryptocurrencies are moved from the exchange to the wallet, you should store your wallet in a safe place along with your passphrases.
Once a hardware wallet is setup, the provate key accessed through a passphrase, which is a series phrases from 12-24 words in length. This is an additonal layer of security for the private key, without it the private keys are lost. To keep this valuable information safe, there are metal plate recovery seed storage that allow for physical, fire and water damage protection.
Other hardware wallets available are:
Paper wallets are another way to store Cryptocurrencies, offline. Sure, it may be the low tech way to do it but still provides a good level of security. Paper wallets have both the public and secret keys and QR codes printed on them and allow storage of digital tokens without any electronic connection. Some paper wallet designs allow for folding of the wallet in easy to transport designs. See this article for more information