Workflows can be shared either by creating a workflow.is link or exported as a .wflow file using "Share as File". Using the latter option, I've set up a GitHub repository of workflows that I've created. I'll be regularly adding to the repository so it's a handy way to always have a copy of the workflows I create.
You can quickly clone the repository using an app like Working Copy (one of my favorite iOS apps). You don't need to be familiar with Git to do this or even have a GitHub account.
Alternatively, you can simply download a ZIP archive of all the workflows. I'd recommend cloning the repository as you can easily keep it updated whenever I add new workflows.