If you're still hanging on to Google Reader, it's time to let it go. After Monday, Google Reader will no longer be available. People with only a few subscriptions will be able to migrate to another service without much hassle, but those with more than just a few will want the option to bulk-import the subscription data. Even if you don't move the data to a new service right away, it'll be nice to have for future reference.
To export your Google Reader data, follow the steps below:
Step 1: Go to Reader settings, then click on the Import/Export tab.
Step 2: Under "Export your information," click on the "Download your data through Takeout" link. You can also go to https://www.google.com/takeout/#custom:reader directly.
Step 3: Once Takeout shows 100 percent and provides an estimate of the number of files and size, click on the "Create archive" button.
Step 4: At the next screen, click on the Download button to download your Google Reader archive as a ZIP file.
Keep in mind that some Google Reader alternatives, like Feedly and Digg Reader, don't support importing subscriptions -- at least not yet. If you think you'll want to try either of those services, you might want to use their Google Reader import options while you still can.