As for me, blockchain.info
is the best way to keep bitcoins online. But for maximum safety you should consider cold storage or even paper storage.
Cold storage is a device where you can send you coins to and keep it offline. Similar to flash drive, but for quite the same. Better google "bitcoin cold storage".
You can also use service which convert your bitcoins to QR-code, then print it on paper and store in your strongbox like usual dollars. Again, google "bitcoin paper wallet".
However, would consider that types of storages if I had 1 BTC or more.
Also, nice option is to split your balance among several bitcoin wallets, it's free, so why not?
Hope it will be helpful for someone who interested in same question.