Finally, I'll talk about specific edits that were made to the draft of "Fourth Wish" I sent Cliffhanger Books. Underlined parts show what changed.
Original: "the imps had attempted to put on five different plays since going to the human world"
Revision: "the imps had attempted to put on five different plays since returning from the human world"
Why the change? I wasn't sure at first, since the imps did in fact go to, and return from, the human world. But they spent just enough time there that I figure the editors wanted to make clear what time frame I really meant--the clock started ticking when they got back, not when they left. Honestly, I don't consider this edit worth making, but I also don't consider it worth arguing about. Part of taking a professional attitude towards writing is picking your battles carefully.
Original: "[Skragg] summoned a window into the human world. Specifically, Candace's home."
Revision: "[Skragg] summoned a window into Candace's home."
This one made me say "Duh." The only time shorter is worse than longer is if every word in the longer version adds something meaningful to the reading experience. The underlined part adds nothing because we know Candace's home is in the human world. There is no such thing as a neutral word or phrase that has no effect on the reader. Every word, phrase, and sentence either makes your story stronger or weaker.
Original dialogue: "So when she turned twenty-one I said, sure, I'll be a guardian, and I had the house inspected and did all the lawyer things..."
Revised dialogue: "So when she turned twenty-one I said, sure, I'll be a guardian. I had the house inspected and did all the lawyer things..."
Candace is under significant stress as she's talking. In my original, she's rambling with long run-on sentences. As usual, I spoke all the dialogue aloud and acted it out in the way I imagined Candace would say it before sending my story to the editors. I'd gotten locked into a way of seeing this scene. The simple edit Kevin and Karen came up with (this one was Karen's) changed my view of how Candace was saying her lines. Now when I act out her lines, I think her dialogue sounds more believable. Why? Because it takes me less effort to say it. I don't need to take such a long breath because her sentences are shorter.
So writers: try speaking your dialogue in more than one way before sending that story out! Try putting pauses in weird places, just to see if you stumble into a pattern that sounds better than your original. It really works.