Yep. Time for more of Beth's unconventional wisdom. (If you don't like it, don't listen, but hear me out).
So you wrote a book. If this is the first time you've done that, chances are it sucks. It's okay. It's tens of thousands of words of experience you wouldn't have under your belt had you not taken the plunge. If you're like me, your instincts are strong enough to tell you it sucks, but maybe not strong enough to know how to make it not suck. You've heard all the horror stories of the dreaded first manuscript. How other writers are so embarrassed by their first ms they wish they hand't shown it to anyone, so you put that horrible first manuscript in a drawer, preferably one with a lock.
The next manuscript you write will be better. While I'm not willing to guarantee it because there is always the exception, it's almost a certainty. However, when you're ready to query that next stronger, better manuscript, you've never written a query letter. Your first query letter will most likely suck too. Why? First of all, they're hard to write. Knowing what to include and what not to is almost an art in and of itself. But also because like writing, and like most things in life, you get better at writing queries with experience. And there are things you can learn--valuable lessons--from a query it's hard to learn otherwise, like taking lots of rejection, what works/what doesn't, how to construct that intro research paragraph about how well you know a perfect stranger.
Your first manuscript has about the same odds of becoming the next bestseller as you do of winning the lottery, but writing a query doesn't cost a dollar. Keep this in mind while querying it (so you don't buckle into a spiraling depression). But you can learn, and what you learn from attempting to market your work is as important as what you learn about your work. Sometimes you get feedback, "I see potential, but ___." No one likes the "but," however that "but" tells you what to improve on next time.
For the record, I did not query my first manuscript, because it sucked. I had a friend who did query her first manuscript, though she later decided it was not so great. However, we started querying our second manuscripts at about the same time, and I was way behind the learning curve on the process. Do I regret not querying that first horrible manuscript that absolutely would not have gotten published? Sometimes. Because I think the experience for my second manuscript might have gone differently if I had. My second full length manuscript, received about 100 rejections. But by the time I queried the last 15 people, I'd gotten so good at queries I had started getting requests. Imagine what the outcome would have been if I'd started querying with that experience under my belt. 85 chances I wouldn't have wasted. I've only queried once since then. The second time I queried three small presses with a short story. I got two full requests. Not bad results.
Did you query your first manuscript?