Well done for getting this far!
In this course we've covered some important elements of professional software development:
I consider these three topics to be essential for effective software development along with version control through a tool such as Git.
You don't need to have tested very single corner of your code and you don't need to have perfect docstrings for your functions but just having something is better than having nothing. These techniques are not about being perfect but simply about being better.
Things to read up on or attend courses about next would likely be:
This course was written by Matt Williams. All text is published under a Creative Commons Attribution 4.0 International License with all code snippets licensed as MIT.
The source for the material can be found on GitLab where fixes are welcome.