Writing a book is one of the most enjoyable experiences I've had. But, as with most things, there are aspects of completing the work that are less enjoyable. For example, I enjoy my work as a therapist. The paperwork, however, makes me want to scream at times.
As writers, getting the story onto paper (or into the computer) is only the beginning. We then begin the process of editing, rewriting, editing, rewriting.... Eventually, if we're fortunate enough, we get to send our manuscript off to a real, live editor.
When my first book was published, I looked forward to the editing process with anticipation. It was one more step toward becoming a 'real' writer (one of the benchmarks I'd set for myself.) I received my manuscript with a note from the editor--she liked my story, but... Then I scanned all the red notations in my book. Now, she'd noted that these were 'suggestions' and that it was up to me to decide what I wanted to change and what I left as I'd originally written.
I did the math on this one. I was a first-time author--green. She was a seasoned editor. I seriously considered every suggestion and accepted all but one. And it paid off.
An editor gives your manuscript a fresh, first look. She or he has not been immersed in your story for months ad nauseum. The editor can give your book a completely objective review and not only find the little nits you've missed, but will view your story in its entirety, assess its readability and your characters' likability.
A good editor will improve your already perfect (in your mind, at least) manuscript. Now, a bad editor will let things slip through and allow you to look like the amateur you may or may not be. A seasoned, talented, professional editor is worth his or her weight in gold. She will oft times save you from yourself.
I just finished the second edit of my soon to be published novel, PIECES. It's due for publication on January 1--Happy New Year to me! My editor caught not only some of the more minor, but important, errors in wording and made suggestions to punch up the dialogue. She also picked up on two major mistakes that would have made readers go, "Huh?"
My advice: When you have a good editor who makes suggestions, give them serious consideration. Read the text from her perspective. And if you feel the editor assigned to your masterpiece is not being helpful, request that your book is reassigned. Now, give good reason for this. Don't put yourself in the position of being 'difficult' to work with. Perhaps the editor isn't as familiar with your genre and it shows (e.g., insisting upon heating up the romance, when your book is not a romance novel). Perhaps when you get your first edits, things now jump off the page at you--things an editor should have caught, but did not. (Although a copy editor will clean this up even further.)
And don't be defensive. If you don't like a particular suggestion or choose not to change something, simply say so and, perhaps, clarify your reason for leaving things as they are. An editor is a valuable tool, but she's also a human being. Treat her as such and nurture the relationship. If she's good at what she does, she will make your manuscript shine!