Encrypt your wallet with bitcoind. Encrypt any backups of the encrypted wallet with GPG. Sign them so you can verify that they haven't been altered in any way and encrypt them to your GPG public key so that only you can decrypt them. With two layers of encryption (and GPG being hard to break, even if you have the resources of a large government) you should be able to safely store backups anywhere.. just don't lose your GPG key.

For large amounts of coins, consider keeping them in cold storage. Print out a paper wallet and keep it in a safe place, or store a second wallet encrypted (again using bitcoind's built-in encryption and GPG.. I worked in the amusement park industry for years so the idea of "redundant safety" has been drilled into my head lol) on a flash drive, then send your coins to that wallet. It's a little inconvenient when you need to spend or trade them, but it's a lot less inconvenient than losing hundreds or thousands of dollars worth of bitcoins.