The first thing I'd like to say to allay the fears of first-time authors and admonish overzealous editors, is that the customer is always right. It's your novel and you have the final say. You could conceivably pay for a full edit of your book and not use it, that's your right to do so and any editor who moans that you've wasted their time isn't worth dealing with. You can avoid this by sending over a sample, perhaps 500 to 1000 words to a few different editors and see if they'll edit it for free as a sample of their work, most will. This will help you find the best editor for you, not the one with the strictest punctuation standards.
Editors, your job is to help the author realise their vision, nothing more, and certainly not to try to realise yours! I always say the best editors are like the best football referees, they're the ones you don't notice. If you rewrite a whole paragraph for some reason, it's likely to be noticeable that it isn't in the author's hand. Similarly if you use words that aren't in the author's vocabulary, or describe a character in a way that they weren't previously.
All changes that are made to a manuscript should be clearly highlighted and trackable, with the option of reverting back to previous versions. It's too easy to lose a line the author is particularly proud of if you don't. Sometimes you don't even need to make a change if it's too destructive, just comment on where you think a change might add something and why. It's best to suggest movement of paragraphs or chapters, rather than swap them around yourself.
Finally I'd like to address an issue that I've seen creeping up a lot online, editors names being listed on stores like Amazon alongside authors names. I don't know whether this is authors feeling like they want to list the kind person who edited their book, or they're coming under pressure from editors to do so. Either way it should NEVER happen. Editors should be like silent partners, they can be thanked inside the cover or in the acknowledgements, but even that isn't strictly necessary.
When I see an editors name listed on Amazon I assume that they've had a much larger hand in the work. For example if the author has just passed a pile of unfinished notes to someone to make into a book. The only time you would usually see editors listed is where a team has put a book like the Guinness Book of Records together, as researchers gather together information and an editor puts it together into a book. Clearly in the case of fiction this isn't what's happening,
Good editors don't need to advertise their services in this way, they can add your book to their editing resumé, a prospective client can always contact the author to verify that they worked on the book. The same goes for translators, unless a book has been or is being translated by multiple people in multiple different versions over time, there is no need to add a translators name to your listing. Doing so will only highlight that the book is not in the author's native language and if anything is a warning sign.
So authors, don't be afraid to use an editor for your work, but stay in control, ask lots of questions, make sure that you're happy with their editing style before you agree to work with them. If you prefer a light touch approach to editing, make sure you get it. Just don't assume you have no errors, we all miss them in our own work, it's just too easy to do. I picked up a book to review only yesterday with an error on page one, don't let your book be the same.
To find out more about my editing services click here, or for my editing FAQs click here.