I bought a coffee machine recently and started to learn how to brew at home. I found the process of learning is interesting: I need some core concepts and key elements, like dial in the machine and make the first acceptable espresso, and then work on foaming the milk, etc.

And then I wonder what is the corresponding process for coding or more specifically for clean code / refactoring. What are these core concepts and key elements that when you spend 20% of your time to learn while get the 80% of the benefits?