Documentation

Each operator should have a descriptive tooltip that an intermediate Blender user could understand without already being familiar with the add-on.

Documentation and help should be linked to in the add-on's preferences. If the tool is complex, it could also be linked to at the bottom of a menu and / or at the bottom of the tool's settings. It should not take up space as a separate panel or tab.

The easiest way to make sure your docs are easily accessible and up to date is to use Read the Docs or GitHub Pages and describe your changes whenever you commit new code.

In addition to explaining how to use the add-on, there should also be a change log in the documentation so that users can check if a recent change is causing an issue or where a feature might have moved to.