Every successful piece of nonfiction should leave the reader with one provocative thought that he or she didn't have before. Not two thoughts, or five - just one. So decide what single point you want to leave in the reader's mind.
Be grateful for every word you can cut.
The game is won or lost on hundreds of small details.
Four basic premises of writing: clarity, brevity, simplicity, and humanity.
Scholarship hath no fury like that of a language purist faced with sludge.
You can solve most of your writing problems if you stop after every sentence and ask: what does the reader need to know next?