It can take some time to find the right editor, so you may want to start asking around even before you have a text that is ready to send. If you know a fellow author who can recommend someone, that’s wonderful, but if not, it’s fine to poke around the websites of some editors and see who appeals to you (and seems to work within your genre). Then contact them by whatever method they request (often a contact form on their site).
An edit is a business transaction. This means that money will exchange hands. Therefore, you need to approach the edit as both a writer and a businessperson (an increasingly common role in the age of self-publishing). Compare the deals you’re offered. Editors with brand-name backgrounds might offer less user-friendly terms (such as hourly rates, which are less predictable than fixed contracts), while less established professionals might offer discounts and extras (such as book formatting and publishing consulting). Don’t be afraid to ask. Hiring an editor is a professional investment. A sample edit will allow you to estimate the value of the service, but never forget about the price.
The greatest benefit of an editor is that he or she is not the author. An editor is someone else. Some editors are professional writers, but every single one of them is a professional reader. As a writer, you’re probably a voracious reader, but you can never be a true reader for your book. By bringing forth a book into the world, you’re asking other people to read something you’ve never read. If you sincerely want the book to be the very best that it can be, then you must ask someone else to read it first. You owe it to your book, to yourself, and to your readers.
Another place to find professional editing service is the team at Ebook Launch. They have a team of professional editors who can polish your book for an affordable price. You can even get a free sample edit of 750 words to help you decide if they're a good fit. The small team at Ebook Launch also provides amazing book cover designs and formatting in addition to their editing service.
Lots of authors I know have a hard time finding an editor because they feel that they want to “know” their editor. This is understandable when you’re entering into a developmental relationship, but copyediting and proofreading are much more technical skills. The best copyeditors and proofreaders I know are freelancers who are hard to find because they’re working for publishing houses, and the only people who have access to them are companies and/or individuals with stables of editors they’ve cultivated over years in the industry. If you find a service (or individual) you trust with access to a stable of editors, be open to being assigned to one. Ask about the individual’s qualifications, and what other books they’ve edited, but let the trial edit be the deciding factor rather than any connection you hoped to have between yourself and your editor.
“My books have very complicated formatting with over 100 illustrations each, external links, and numerous bulleted lists. None of the formatters I contacted would even take these on but John said “No problem!” He completed my original three e-books quickly, for a more than fair price, and they look great. I have no hesitation recommending Ebook Launch’s work to other e-book authors!”
I cannot speak for all editors, of course, but I know I and many of us would be open to editing just part of your book at first, say, a particular chapter or two that you sense needs a lot of work. That is often enough to show you mechanical errors that you tend to make repeatedly. You can then go through the entire manuscript yourself looking for as many of the same kind of errors as possible. You will sharpen your basic writing skills in the process, and it will pay off in all future projects.