A developmental editor as gentle as a kitten
If your developmental editing feedback doesn’t make an author feel eager to get to work revising the manuscript and instead makes your author depressed and reluctant to work on the manuscript, then maybe you’re doing something wrong.
When I’m working on a developmental edit—that is, editorial feedback on major elements such as characters, plot structure, and dialog (rather than grammar and spelling)—I typically mix in a lot of praise with constructive criticism about how the manuscript can be improved. Even as I do this, I sometimes think this praise is useless fluff. Perhaps the praise isn’t as necessary as pointing out how the book or story can be better, but it instills a sensitive author with confidence and encouragement. This is important, believe it or not.
Back in my undergraduate days in the early 1990s, I had a college instructor who was great at giving such feedback. No matter how much the story needed improvement, no matter how rough it was, this instructor got me excited to run to the computer lab or to my dorm room and get back to work revising that story. That’s the best way to do a developmental edit.
That constructive criticism sprinkled with praise is infinitely better than getting developmental feedback that leaves the author feeling battered and believing it’s not such a worthwhile writing project after all. Developmental feedback that’s abrasive, snarky, sarcastic, and/or impatient rubs the author the wrong way. Accusing the author of not writing in a scene or detail that they did write but that you skipped over also rubs the author the wrong way. Doing all that and/or refraining from supplying the author with any praise, not so much as a, “This is a very promising beginning and I’m looking forward to seeing a later draft!” also rubs the author the wrong way.