Write well. Write often. Edit wisely.
The benefits of a professional edit by an experienced editor are many, from the basics of correcting spelling, punctuation, and grammar to the more complex issues of adjusting plot and characterization and pacing and tone.
An editor is that second set of eyes that every writer needs for his work. No writer of long fiction will find every error in his own writing. (And unfortunately for those of us wanting perfection, most novels are printed with errors.) The experienced editor is trained to see errors and, even better, knows how to correct them, can often show you several options for correcting problem words or phrases or scenes. An editor is also impartial—he or she will not feel the same attachment for pet phrases that the writer has. Such an attachment on the writer’s part may well prevent him from deleting wording that hinders rather than benefits his story.
Yet, paying a professional editor is not the only option for writers. A critique partner—one who is free to tell you what’s wrong with your story—is a great alternative. Trade critiques with a friend or find a partner through Internet writing groups. Join a local writers group and share your work there. Keep in mind, however, that other writers may not give your work the same detailed analysis an editor would. They may have neither the skill nor the interest. What they can provide may be enough for your needs. Just keep the limitations in mind.
So, should you pay an editor to go through your manuscript?
If you’ve never studied writing either formally or informally, yes, consider a professional edit. Treat the experience as continuing education.
If your query letter and synopsis get you repeated requests to submit a partial or full manuscript but your submission is rejected again and again, consider a professional edit.
If you’re a quick learner or one who learns by example, consider an edit. After one in-depth edit, you may be able to take what you’ve learned and apply it to subsequent manuscripts.
If you’re self-publishing, by all means consider a professional edit. As I mentioned earlier, everyone needs a second set of eyes to examine his work.
If you’re writing for your own enjoyment, don’t have plans to publish, or just don’t have the money to invest in a freelance edit, consider other options first. A good edit is worth the price, but you may have other considerations or circumstances that trump the benefits of an edit.
An edit for your novel manuscript is an investment. An investment in not only one project, but in your career as a writer. I recommend that, when feasible, you make the investment at least once in that career.