You might want to search online for sample query letters. That's how I learned, and I also went to a presentation by the Book Doctors for a Pitchapalooza.

Like Olivia said, what is it about and why would anyone read it?

- What's it about?
- What's it like? (similar books)
- Why should anyone care about _____
- What's the problem that needs to be solved or the dilemma? (likely to be your hook)

For non-fiction, the query should include what the reader gains from reading the book.

Jon Gibbs (an author who is an entertaining speaker too) suggested, give them your main character, give that character a problem, then a bigger problem, and then hit them with an even larger problem that makes the other two look like child's play. Leave whoever reads/hears that query wondering how is this going to be resolved - and maybe you'll get an email or phone call.

Sharon from New Jersey
The End of the World Sucks