You want the query letter to be less than one page, an interest-getter. Here are some good examples --
Sample Query Letter
(scroll down for the sample)
Here's a query letter from another site (and don't forget to use a business style in writing your letter) along with a comment from the site at the end --
Sample Query Letter # 1: Fiction -- Novel
Dear Editor [use an actual name]:
My grandma says time don't run but one way, but that summer was one where at times I wished it wouldn't run at all. Just hold still on Saturday nights when the best thing to do was fly down dark roads in Billy Clodfelter's Lark with the windows rolled down and the music up. Stop on Sunday mornings when Mary Barrier smiled at me over her hymnal. Just stay at the time when things still seemed simple.
Jake Hanson has always helped his dad on his rounds of the juke joints and pool halls of Cap Rock, Georgia, changing the records and collecting the cash. He always thought he would take over the business someday, but now at 14, he's beginning to really listen to some of the people and the music they make. He also begins to question why some customers are treated differently, especially in the black sections of town. When he hears Belinda Triplett singing in a way he's never heard on any record, Jake knows he wants to be something more than just a juke box man.
Set in the early '60s,
Juke Joint is a young adult novel of a boy finding his own path in a turbulent time. Jake and Belinda are strong characters whose growing friendship flies in the face of the conventions of their small Southern town. Not just a romance or a problem novel,
Juke Joint explores the issues of racism and family loyalty against a setting of church socials and midnight drag racing, gospel and rhythm and blues.
I would be happy to send the manuscript to you for consideration and have enclosed a reply card for your convenience.
Very truly yours,
[Your name]
A fiction query letter might be the toughest kind to write. It should be short, but contain enough of the sense of the story and your writing style to catch the attention of an editor. Since so much of fiction is a matter of taste, the letter needs to be targeted carefully. Think about what sort of copy entices you to check out a book by an author you have never read before. Sometimes including an excerpt from the manuscript can be a good approach--for example the beginning paragraph if you have a good hook.
Query letters for fiction are worth a bit of angst and extra polishing. Reading a novel requires a larger investment of time on the editor's part, so the query letter must be targeted very carefully. Don't send a serious issue book to a house that does only series romances.