There is no method which is 100% safe for storing our coins, but we can try these method that the hackers cannot penetrate our funds. First, Offline key generation and storage. Then, Encryption is useful against theft. In addition to your private keys the thieve will also need to know the encryption (which is usually a password) to spend your coins. Lastly, Back-ups of your private keys decreases the chance of you losing your coins due to hard disk faillure, natural disasters and your parents throwing away your stuff. But having back-ups also protects you from yourself. We can be forgetful or sloppy sometimes.