Pat yourself on the back.   Curtsy.  Take a bow.  If you’re like me, mistakenly mourn the end of your journey.  (Don’t worry.  It’s not the end.  You’ll be spending the rest of your life with your characters.)

What’s next?
No one wants to hear this, but it’s the truth.  Let the book sit for as long as you can manage.  Do something, anything, else.  Take a break.  Drink a beer.  Play CatchPhrase.  Go dancing. 
Tic tock.  Tic tock.  Your dancing shoes have worn thin.  The beer is warm, and your friends are tired of you being a whiz at word games. 

Pretend you’ve never seen your novel before.  Read it with fresh eyes.  Find every flaw and fault you can.  Be good to yourself and STAR the parts you like.  Cut what is unnecessary to the plot, the stuff you love, but doesn’t help forward your novel’s storyline (kill those little darlings).  Revise and rewrite.  Repeat.  Revise and rewrite.  Repeat.  Be your biggest critic.  If you can, have other writers or readers read for you.  Talk to them.  Don’t be defensive.  Get as much feedback as possible so that you can see when there is consensus.
Let it sit again.
Finally, lock yourself in a room for as long as possible.  Stay sober (while writing).  If you smoke cigarettes, smoke up.  Be your harshest critic.  Tell yourself, “I can do this.  I can make something that is undeniably good, that no one will dismiss. I can do it.”  Confidence goes far when it’s you and your pages alone in a room.   

Next, leave your creative muse behind.  I call this the 
BUSINESS STAGE  (I never much cared for this stage.)

Use the Writer's Market or to find the agent that fits.  Make sure that your agent reads the kind of prose you write.  Make sure that your agent is accepting unsolicited manuscripts.  

Google "How to write a good query letter."  There are a million links.  Then, get to it.  
Write a fabulous query letter (no first drafts here).

This is my query letter that got my first book (and me) pulled from the slush pile.  

Dear Ms. Brower:
Please consider representing my novel, The Handbook for Lightning Strike Survivors.
A literary novel, The Handbook… spans nineteen years in the lives of the two main characters (Becca, born into privilege in 1969, and Buckley, born into poverty in 1959), and suggests that people, however disparate, are linked. The 400-page narrative encompasses multiple themes, but ultimately the book is a story of redemption.
Buckley, whose mother is struck dead by lightning, writes a nonfiction handbook, The Handbook for Lightning Strike Survivors, excerpts of which appear throughout the novel. Becca, a repeat lightning strike survivor, buys Buckley’s Handbook through an ad in the back pages of a magazine. Becca and Buckley, destined to collide, meet during a massive electrical storm where there is a surprising reversal of fortune.
Structurally, the novel tells Becca’s story, then Buckley’s—the tension mounting until the two meet.
I am a thirty-four year old MFA fiction graduate My screenplay Spotting Normal was a 2003 semi-finalist for the Chesterfield Writers Film Project Award and a 2004 finalist for the CineStory screenwriting award. My story “Cop Drag” was a finalist in the First Annual Lewis Nordan Fiction Contest sponsored by Algonquin Books. My second screenplay, Paint Spain With Bart, was a finalist in the 2006 Screenplay Festival Contest sponsored by InkTip. I am currently halfway through my second novel.
Let me know if I may send you the first 100 pages or the full manuscript.
All Best,
Michele Young-Stone

Now, mind you, I can see a dozen + ways to revise this query (nowadays), but it's mine.  It got me where I am.  I just heard a funny Turkey Day story from my dad.  He asked a woman if her boobs were real, and she said, "they're mine."  Enough said.  This query letter is mine.        
Here are some query letter tips from our own girlfriends, a blog from August, 2011.
Here is a link to an article by Chuck Sambuchino in Writer’s Digest.  My query letter appears with my agent Michelle Brower’s response as to why she requested a partial manuscript.

If an agent wants to see your manuscript, go "Whoop whoop!" and then calm yourself.  You've got a bite!  Revise again.  This could be your big break!  

If you get a rejection slip, don't cry.  Try try again.  Here's a video I made about my personal rejection journey and publication:

Happy Black Friday, gang, and thanks for letting me share some tips.  

Michele Young-Stone, author of The Handbook for Lightning Strike Survivors (2010)

"Young-Stone has written an exceptionally rich and sure-handed debut, full of complex characters, brilliantly described..."  The Boston Globe

"...a book filled with characters so imperfect, they look like you and me."  The Raleigh News & Observer

"The sense of melancholy, tempered by the resilience and heart of the characters, makes this ripe for Oprah or fans of Elizabeth Berg or Anne Tyler."  Starred Review, Library Journal