What do you wish more programmers knew about?
Mainly curious about things that annoy you when your coworkers do them, stuff that makes code hard to understand/reason about.
I wish more of my colleagues used early returns. I regularly find myself four or five levels of indentation deep because of nested if statements when we could've bailed 30 lines ago and saved the cognitive load.
Maintainability matters.
Sooner or later someone else - perhaps under duress - will have to do something with you code.
Assuming everything is obvious is a bad assumption to make.
Kludgy code. Cargo culting. Lack of commenting & docs.