on Writers Helping Writers:
Many writers equate preparing for a professional edit with revision. We’ll cover a few revision tasks in this article, but revision is only half the battle.
Preparing your manuscript is the first part of getting ready for editing.
The second part is preparing yourself.
Knowing when a manuscript is ready to be sent off for editing is fairly straightforward. The manuscript should be thoroughly revised, incorporating a close review of the plot, character arcs, story, and writing, outside feedback, and a healthy dose of author-powered proofreading. The manuscript you submit for editing should be the very best ambassador of your storytelling and writing abilities it can possibly be.
Knowing when you yourself are ready for editing may seem less obvious. You could choose to approach editing as a brief but unpleasant course of medicine you should hold your nose and chug as quickly as possible. Or you could choose to make more of it, as a relatively rare window allowing you to peer inside your writing in a new way. You, as a writer, are ready for editing when you’re warmed up and ready to grow.