The best way to securely store cryptocurrencies is to store them in cold storage, such as a hardware wallet or paper wallet. Cold storage is an offline method of keeping coins safe from malicious attacks and thefts. Using a hardware wallet or paper wallet allows you to keep your coins offline, meaning they cannot be targeted or stolen by hackers. Other security measures such as using strong passwords, 2-factor authentication, and encrypting your wallet are also important steps to keep your coins secure.