I hate to be the "it's complicated" guy but "excellent" is too broad. I see every day code that is elegant but has bugs, ugly code that is foolproof, optimized

I hate to be the "it's complicated" guy but "excellent" is too broad. I see every day code that is elegant but has bugs, ugly code that is foolproof, optimized code that performs abysmally because of some architecture change that happened in between, and a lot of abominations that make the code bad for guy A and good for guy B (e.g. a neat typechecked, object-oriented, very elegant, Pythonic numerical code that is 100 times more confusing for your research level numerical analyst than an uglier but functional Matlab script). What I agree on is "the best way to improve X in my code" is "read code that has quality X". Given the broadness of your question I suspect you are still finding your way around programming in general. If that's the case my method is to be driven by curiosity. - Why does macOS behave this way? Let's look up xnu's code - I wonder about list implementation... Let's look at cPython code for appending items to a list And so on... There is a lot of open code for stuff we are using everyday. It is interesting to get into it.