I am copying this from a post on Janet Reid's blog. Click here to read the original post. I recommend all submitters to read this and revise your query based upon these suggestions before posting here for additional critiques. This is very sound advice:
Here is the outline [Ms. Reid uses] to teach the class [on Effective Query Letters]:
1. A query letter is a business letter
2. A query letter requires "show don't tell" just exactly like your novel does
3. A query letter MUST tell an agent what the book is about.
3a. Who is the main character?
3b. What happens to her?
3c. What choice does s/he face?
3d. What terrible thing will happen because of that choice?
4. A query letter should include the word count, the title and any publishing credits you have? Don't have pub credits? Don't worry. Don't reach either.
(the novel has to be finished. You don't have to say it is, but just know it)
5. A query letter must avoid several instant-rejection phrases:
sure best seller
"dear agent"/"dear sir or madam"
6. Things to avoid in query letters:
Don't demean yourself.
Don't quote rejection letters
Don't quote critique groups, friends, paid editors or conference contacts.
Don't ask rhetorical questions.