In one quote, the essence of writing

Writing is linear and sequential; Sentence B must follow Sentence A, and Sentence C must follow Sentence B, and eventually you get to Sentence Z. The hard part of writing isn’t the writing; it’s the thinking. You can solve most of your writing problems if you stop after every sentence and ask: What does the reader need to know next?

~ WILLIAM ZINSSER

• Also read: "William Zinsser: Lord of the Language".