The safest option is to use a hardware wallet, which is a special device that stores private keys and signs transactions, but never exposes the private keys to the computer or the internet. This is one of the safest ways to store bitcoin, as it is immune to many of the dangers that threaten online wallets. It is important to remember that the loss of the physical medium on which the private keys are stored means that the bitcoins associated with those keys are lost forever. That's why it's important to take extra precautions and possibly keep multiple copies in different locations.
The beste hardware wallets of this moment
Blockstream Jade, now available in multiple colours
Blockstream Jade is an easy-to-use, purely open-source hardware wallet that provides advanced security for your Bitcoin.