My primary source for usage, formatting, and other editing issues is the Chicago Manual of Style. I also use William Strunk & E.B. White’s Elements of Style and recommend it to nearly everyone I work with. If you don’t have The Elements of Style, buy your copy now.
Why? Because so many people love participial phrases. But they write things like “Entering the room, the light followed her across the floor.” If you do this, I’ll write you a note: As written, the light entered the room. See Strunk & White, Rule 11: “A participial phrase at the beginning of a sentence must refer to the grammatical subject.” (If necessary, I’ll tell you what a participle and a subject are, too. As one of my authors said, “Oh—that’s what my sixth-grade teacher was talking about!”)
I also refer authors to Rule 17: “Omit needless words.” That is, don’t overwrite. Overwriting is OK in a rough draft, of course. You’ve got to get all your thoughts out of your head and into a Word document. Editing is the strainer that lets excess words go down the metaphorical drain.