You can always add more security. Depending on the amount I can think of several ways to improve it:
Additionally:
- Verify both your Electrum download and your Linux OS download against the provided GPG signature files to ensure authenticity. This is very important and shouldn't be skipped.
- Optionally, I would also physically open my computer and unplug/disconnect/remove any connectivity hardware such as WiFi or Bluetooth chips, as well as any hard drives or other storage, in between the online and offline steps.