As an editor, I go through a lot of query letters and over time I've learned that certain problems in query letters translate directly into similar problems in the actual books the query letters are about. Here’s some advice to help improve your query letters and hopefully even your stories.
A good query letter is like the little free sample tables you see at the grocery stores. It needs to be professional but friendly. The most effective thing it should do is give a taste of what your writing has to offer. It would also be good to mention a few ingredients, like what genres, emotions, and characters are in the book.
To give editors a good taste of your writing, you need clarity. Bad query letters are often vague about important character or plot points. Mentioning things like big decisions, threats, and changes are as common as salt or sugar in foods and won't really make an editor hungry for your manuscript. I've also noticed that when the query letter can’t explain some aspect of a book in an exciting way, that same aspect is generally lacking in the book itself.
Having vague concepts in query letters is like watering down the taste while having focused specific details is like giving them a full burst of the unique blend of flavors that your writing will bring.
Instead, be specific. What are the particular big decisions that have to be made and why do they matter? Who are we going to follow through this book and what sort of person are they? Are they someone that feels real and fun to read about? Is conflict there because the plot demands it or has it carefully been grown out of the characters, ideas, and world of the book?
A clear concise query is like that great sample at the supermarket. A great sample helps show how amazing the taste of a product is compared to other similar foods so the customers can buy it. For query letters, you're also trying to show how your particular blend of words, characters, and plot will provide a different and better fare than readers have already tasted over and over by pulling out little pieces of the ingredients that have gone into your book.
So before submitting, be sure to pack all the flavor your book has to offer into a short, powerful query. With any luck, it will be one that makes editors’ mouths water.