I've been reading "The Subversive Copy Editor," by Carol Fisher Saller, chief grammar guru at the Chicago Manual of Style. The graphic designer colleague who recommended it said, "After reading it, I feel horrible about what I've done to your copy!" We worked together in a high-stress, this-should-have-been-out-last-week environment where there was never time for the copywriter to proof; I just sent out my plain-Jane Word docs and hoped for the best. Often, the designer would have to decide herself where to trim or ad copy depending on the design. She's smart, so it usually went fine. But as a writer, it can be devastating to know your words are being chopped and diced without you getting the chance to put a Bandaid on it. And since I do copyediting as well as writing, the book is doubly interesting to me. Copyediting could, in many hands, be an awfully dry subject, but the author is quite charming ("Now that I think about it, contacting a writer for the first time is much like answering a personals ad . . .").
And most helpfully, her advice also extends to working relationships writ large as in:
"Write or email after you've looked over the project but before you start editing. The writer is going to be your best ally as you work, so establish cordial relations. . . . Show that you've familiarized yourself with his work by asking a question or two, and let the questions show your knowledge and competence.
. . . .
Asking questions like this at the beginning will help give the writer confidence that you will pay attention to detail as you whip his stuff into shape. . . . And it will demonstrate your willingness to listen and negotiate."
I think that's good advice for any new project with a client.