A message from Hobblebush president Sid Hall
Advice about query letters is easy to come by, it seems, but here's my two cents worth as someone on the receiving end.
Getting a query from someone who is taking a long shot on a publisher is not only a waste of time, but is annoying. So thoroughly study a publisher's books and the markets for them, not to mention their guidelines. If the book doesn't fit what they do, don't try!
I always look for three things: What's the book about? Who will want to buy this book? What credentials does the author have? Get the essential information, the genre and what the book is about right up front and then go into the rest.
Most of all, the query is a demonstration of talent. It only takes a sentence or two for an editor to see if someone knows how to write. Personally, I'm not looking for someone having slaved over the language. I'm looking for innate writing ability, devotion to writing, or experience.
It helps if the tone of your letter catches the tone of the book. When Jim Salmon queried about his book, in addition to a tantalizing description of his round-the-world voyage he wrote this: "One reviewer of Rime said it was '…insightful, funny, and well written.' The fact that she's my daughter did not influence her in any way." I fathomed a lot about Jim and his book from that.