If you are too nervous to store your bitcoin keys digitally, for fear that they may be stolen by hackers, there is another option: ‘cold storage’. Cold storage wallets store private bitcoin keys offline, so that they can’t be stolen by someone else on the Internet.
It’s a good idea to use cold storage for the bulk of your bitcoin fortune, and transfer just a little to separate bitcoin addresses in a ‘hot’ wallet with an Internet connection, making it easy to spend. That way, even if your mobile phone is lost, or the hot wallet on your notebook PC is erased during a hard drive crash, only a small amount of bitcoin cash is at risk.
Many software bitcoin wallets feature a cold storage option. Or, you could go completely analogue, and simply use paper wallets for offline storage.