As promised, here is a piece on crafting that query (or blurb) to get agents, editors, reviewers and (most importantly!) book buyers excited about your book.
Writing the Badass Query

By Niklas Bildhauer (who also is User gerolsteiner91. (originally posted to Flickr as folder) [CC-BY-SA-2.0 (http://creativecommons.org/licenses/by-sa/2.0)%5D, via Wikimedia Commons
Your book is done. You’ve written it, rewritten it, had it critiqued and maybe even edited professionally.
You’ve printed it out and read the whole thing aloud: to your mother, your cat, and your toughest crit buddies–not to mention the Philodendron. You’re at the point where you’re just pushing commas around.
You know what that means?
You’re ready.
The Hook

By Parrot of Doom (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)%5D, via Wikimedia Commons
How long did it take you to decide?
It started with a sentence, a handful of words. Maybe it was enough to make you catch your breath. It was at least enough to make you read the next line. And the next, and the next, until before you know it, you were standing at the checkout holding out your debit card.
Now that, my friends, is a proper hook.
Pitch Perfect
As writers, we all know you’ve got to show and not tell. But a pitch is different, right? After all, you’ve only got a page. If there was ever a case for telling, now is the time, right? Wrong.
Now is when you absolutely must show. Don’t tell them your protagonist struggles with loneliness and can’t find the right guy. Show her in the checkout line, juggling four pints of Ben & Jerry’s while eyeing the douchebag with the $200 haircut. Meanwhile the cinnamon-sweet cashier can’t catch her eye.
That’s all there is to it. Build a collage: a sketch of character, a shadow of scene. Arrange a few powerful verbs around one glistening metaphor. Sculpt the shape of your story like that—the first third of it at least—and leave the reader with a breath of hint of what’s to come.
Now, finally. Make it sound like you and make it match the tone of the book. Funny book? Funny pitch. Scary book? Scary pitch. You’d be surprised how many people miss this.
All right, got all that? Great. Now do it in 300 words. Easy-peasy, right?
The Shameless(?) Self-Promotion
If you’re doing a query letter as opposed to crafting a pitch for Amazon’s Breakthrough Novel Contest, you’ll also need to talk about you, the writer. The same rules apply—don’t tell them about your immense talent, your sparkling prose or that your characters are thoughtfully crafted. You should have shown them that in the preceding 300 words or so.
Awards and writing credits, if you have them, are a fair brag. But don’t tell them your story is impossible to put down; make your query impossible to put down.
The Final Dos and Don’ts
Did you ever wonder why literary agents hate rhetorical questions? Don’t.
Do you think your novel is so ground-breaking it merits a two-page query? Don’t.
The Dos?
Proofread your query 1,001 times. Once you’re convinced it’s perfect, have it proofread by someone else. Lots of someone elses.
You only get one chance. One single chance. C’mon, you busted your behind to write that book, it deserves the best pitch you can give it. Write one so good it blows their hair back.
I’m counting on you.