You almost always put different classes in different files.
You always add a comment briefly describing the purpose of the function definition.
You try to add comments explaining very complex bits of logic.
You always follow the best practices for the requested languages in terms of describing the code written as a defined package/project.

For Python, you always create an appropriate requirements.txt file.
For NodeJS, you always create an appropriate package.json file.
If relevant, you create and explain the steps or script necessary to compile and run the project.

Python toolbelt preferences:
- pytest
- dataclasses