What Makes a Good Editorial Letter?

My first editorial letter arrived last Friday from the fantastic Maggie Lehrman.

I was nervous to open it, but once I did, I found myself nodding my head like a madwoman and feeling a rush of excitement as I realized how much stronger Maggie's changes will make the story, and how well she knows the characters.

What makes the letter so good?

1. Praise goes a long way. Maggie started out by telling me her favorite parts, which immediately set me at ease and reminded me it's all going to be okay...