That’s a great point about other disciplines. Why should writing require some outside arbiter? Is it because these other disciplines consist in crafts that require significant training, whereas anyone who’s literate can start writing a book at any time (and therefore, the threshold for entering the medium is much lower)? I do hope you’re right about learning self-editing skills. I actually just made a YouTube video about how to self-edit: https://www.youtube.com/watch?v=3mmLEuH9x28
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.
If neither Sally nor myself feels quite right for you, then I suggest you browse the bookstore or even the public library for books published in the last few years that remind you in some way of yours. Check the Acknowledgments page to see if they thank an editor. If not, see if there is any information to contact the author and ask if they used a freelance editor and if so, would they recommend them.
An extensive critique of my first novel led to major changes in the format. I was very fortunate to have an experienced novel writer to give a detailed analysis, with corrections. I did not fully appreciate, at the time how valuable this process was, but do now. You need to acknowledge that there are likely to be inconsistencies leading up to the final manuscript and be prepared to make drastic changes. An editor is attuned to picking up on these, where you have accepted the script , even after numerous re-writes!
I used Ebook Launch to format my first book, a novella entitled His or Her Betrayal for both ebook and print, and I was happy with my results. They are very professional and get the work done in the amount of time that they tell you. I just submitted my second book Love, Lies and Heartbreak, which is a collection of short-stories for them to format for print and ebook as well. I'm sure I won't be disappointed in their work. They are my permanent source for formatting my books. Thanks so much for your great work guys!!
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.
When you get that email, particularly if it's your first book, make sure you are well-rested and in a positive frame of mind before you open it. If it’s your first book, the editing process will be hard on your ego, but remember, the editor’s job is to make your book better and help you learn the craft. You are paying for them to give you critical feedback, not to pat you on the back and say ‘good job.'