My takes from this book, relevant to scientists:
1. Writing is a craft, and like any craft it can be learned.
2. Good writing = good thinking. Muddled brains write muddled sentences.
3. There needs to be "joy" while writing. If you feel the drudgery, your reader will too. Usually you will need to force yourself to be joyful. Apparently most good writers do this.
4. In the end all writing is for yourself. Though you want to have a general audience in mind, you cannot write to specifically impress the editor or reviewer (a "rebuttal" may be the only exception). You need to write for yourself.
5. This is the most important thing to realize.....IT'S HARD WORK. Clear sentences are no accident, they are a product of innumerable revisions.