[smailq]

Fully understand what each line of the code does.

Third party libraries, copy & pasted code from Internet, helper functions from a framework, and more often hides critical information the coder needs to be aware. Many inexperienced coders simply put together code and produces working code without good understanding of why/how their code works.

I found that deeper understanding of the code not on the first level but all the underlying libraries and functions, lets me write more concise, bug resistant, and easy to understand/maintainable code.