Good writing, simply
Good writing is simple and precise.
Every word serves a purpose. When three words convey the same message as five words, good writing chooses three words.
Good writing uses plain language. The medium gets out of the way so that the ideas can stand on their own. It uses jargon only when it improves clarity.
Good writing comes after the first draft. It is the product of polish through revision.
Good writing breaks rules. But one must first learn what the rules are, so as to break them intentionally.