Learning functional programming will make you a better developer in all languages IMO. This is the single biggest vector for understanding how to write maintain

Learning functional programming will make you a better developer in all languages IMO. This is the single biggest vector for understanding how to write maintainable code. Similarly learning design patterns will probably make you a worse programmer but learning the heuristics behind them (eg composition over inheritance) will make you a better programmer. Learning DDD will make you a better programmer by understanding how to use bounded contexts to manage complexity as software grows.