When your data is in the cloud, you're relying on someone else to back up your stuff. If your account gets hacked or the service glitches, your data could go up in a puff of smoke. Revert.io automatically backs up your Evernote, Tumblr and other data online.
Revert.io is similar to previously mentioned Backupify, but covers different services. The free version of Revert.io backs up Evernote, MailChimp, Tumblr and ConstantContact for 30 days. If you upgrade to the $US9.99/month paid version Dropbox, Highrise and Pipeline are added.
You could sync the data to your computer and back up locally, of course. Backupify gives you more version history and cloud-based restores in a disaster. The service uses data at rest and in transit and keep your data private and supports two-factor authentication.