Resources for writers on this site include:
Commonly Confused Words: these are pairs of words that people often get confused.
The Seven Point Story Structure: a summary of Dan Wells’ talks on plot structure.
The Well-Presented Manuscript: a blog series (now a book) which covers the most common editing errors and how to avoid them.
Writers may well be interested in my posts filed under the categories Manifesto-esque Rantings (so called ironically) and Craft. I’ve collected other resources for writers that I posted on the late lamented Google+ social network here.
My wife and I also run a copy editing and proofreading service.