For someone that has provided copyediting and proofreading services to clients for a few years now, I cannot stress enough on the need for a final check by expert eyes on the language and flow of your copy when working on newsletters and brochures, especially if they are external facing, for marketing to clients and other interested parties, but also if they are intended as internal communications for staff or shareholders.
Nope, not doing it, but I am helping a client edit and proofread their book on technical writing which is turning out to be quite the eye opener. It is a great effort, lots of information written in a clear and concise manner, very interestingly explained with images and graphs and such. My client has sure put in a lot of effort so I am hoping I can do a good job with the editing part of it. Have to deliver in about 2 days so I will sign off now and focus on that :)