Deirdre McCloskey’s short Economical Writing is one of the best writing guides there is. One reason is that it is, in fact, a guide. It is not a manual. It is not filled with rules and procedures that one must follow… or else. Instead, much like McCloskey’s own writing, it takes a less rigid approach; good writing is anything but rigid. McCloskey shows her suggestions in action, and shows the reader common pitfalls they are better off avoiding. But she rarely commands.
And as it turns out, Economical Writing is now available for free online. You can read it right there on the web page, or you can download it.
Highly recommended reading for anyone interested in becoming a better writer.