If you're involved in Deep Onion Coins this video guide will show you how to backup your wallet.dat file, and your private keys.
I recommend doing this after receiving more than a few coins. Keep it regular, keep yourself safe!
Please make sure that after you've backed up your wallet .dat file, and your private keys that you save them somewhere safe - Not on your desktop as I did in the video. I recommend buying 2 cheap 2 or 3gb jump drives and back up your keys/wallets to it. Make a copy and save is somewhere safe - hence why I say grab 2. That way, if one either a) goes missing or b) becomes corrupt, you always have a backup of the backup.