For many years I was a copy editor. That’s good honest work and underappreciated, but above all it’s a great place to learn how writing works. From character—is this the right punctuation mark? is this word spelled correctly?—to clause, from sentence to paragraph, from passage to complete manuscript, a copy editor tinkers with prose like a jeweler with a watch. It’s great experience, and great training for a writer. Learning to copyedit before becoming a writer is like being a mechanic before learning to drive a race car. The understanding of the secret processes behind the magic can only help, especially when the handling gets rough.
—Scott Huler, as quoted here:
The mechanics of good prose: In praise of copyediting (The Mechanic & the Muse)