I don’t care how good you are, you need another pair of eyes to fix problems in your ms. You’re too close to the product, so you’re gonna miss a lot of stuff. You’ve seen the errors so many times as you worked your story, that they look like they belong there.
Don’t try to get one editor that will do everything. The personality traits that make a person good for one type of editing are usually in conflict with what it takes to do the other.
For instance, I’m a damned good copy editor. I have a professional background that taught me to delve into things at a “micro” level (computer programming). In doing so, I often lose track of the overall picture. So, that makes me marginal at best as a story editor.
Also, it’s almost impossible to do both jobs in one pass (for the above reasons). A person really has to focus on either the high-level aspects of the manuscript or dive into the mud to sort out the worms and beetles.
Story editors come under a number of “labels”, such as “content editor”, etc. You’ll have to look around for them.
Story editing is a high art form and requires a solid background in fiction writing and construction. Finding a good one can be a daunting task. The best advice I can give is to talk to other authors who have used content editors and get recommendations.
Or, you can try to get Sara Dean to do a story edit on your book. Her rates are reasonable, but she’s very busy trying to balance writing, managing a home, husband, and active children, along with her part-time job as editor. I can get you in touch with her (she doesn’t maintain a blog at this time).
Expect to pay more for a good story editor than for a copy editor.
As I mentioned earlier, copy editors wade in the mud of the ms, searching for punctuation problems, spelling, tense problems, active vs passive sentence structure, weak verbs, better ways of conveying a meaning, and eliminating surplus dialog tags and “Tom Swifties”. The really good ones will be on the lookout for problems in facts as well as inconsistencies in the ms (the main character checked his gun at the door, but suddenly draws it from his pocket and shoots the bad guy).
Good copy editors are worth their weight in gold (of course I’d say that – grin), but don’t command the fees of a good story editor. This is because it takes less talent to be a copy editor; just a lot of experience and a good command of English. We’re an unappreciated lot, but there are more of us, so competition keeps the price down.
Again, get references and peruse the books the editor has worked to see if his/her work is any good.