Amy Einsohn may not be world-famous in the A-list Hollywood sense, but she was a revered mentor for nearly anyone in the copyediting field. Her book, The Copyeditor's Handbook, was required in all of my copyediting courses and I found her information to be invaluable.
After learning the rules set out in the various style guides, most of copyediting work has to be learned on the job. The Chicago Manual of Style can only take an editor so far. These days, with freelancers like myself, typical on-the-job experience is non-existent and we have to piece the copyediting business together ourselves.
But Amy's book is very much like taking a copyediting course in itself. She breaks down the business into an easy process without all the fluff of self-promotion or chapter-on-chapter of why we should be reading this book (as is common in many creative writing books, but that's a rant for another day). It serves as a great companion to both copyediting courses and students who may want to self-teach.
Amy humbly offered up her years of experience to aid other fledgling editors through her book and personal interactions. Most people don't think about copyediting on a daily basis, but I can assure you that many authors who have hired great copy editors probably have Amy Einsohn to thank.
I have to note here that, even if you choose to self-publish, I highly recommend hiring a copy editor or even a content editor (or someone who can handle both). I am not writing this to promote my own business, but to promote practical advice. Even copy editors have a difficult time editing their own text. The fact that there are so many e-books with so many blatant mistakes proves that copyediting is still worth the money. If you are unsure of a copy editor's skill, send them a sample to edit before committing.
It's not too late to get to know Amy. Here's an interview she did after the publication of the third edition of her handbook.