Learn how to write good tests. This includes writing tests for code that doesn't have tests (often requires refactoring or some careful engineering) And possi

Learn how to write good tests. This includes writing tests for code that doesn't have tests (often requires refactoring or some careful engineering) And possibly writing tests before you even have the code aka TDD (although I'm not on that bandwagon I have done it at times with great results). If your code is easy to test it is probably better code than otherwise. Also depending on the organization a-careful-not-very-productive programmer can be worse than a loose-prolific-code-cowboy but generally that is not the case.