As with so many other things I've discussed in previous pages, every editor and agent has specific requirements for what they want to see in a query package. The simple truth is, none of them get upset over a single page query letter. Other want to see more. Also, if you're emailing the query rather than sending it by mail, you will benefit from a much shorter attention span on the part of your audience. Emailed queries must grab their attention right away.
It is very rare that you will be asked to send in the entire manuscript after a positive response to a query. Usually you will be asked to send in a cover letter, a two-page synopsis and three sample chapters.
The cover letter is critical. This demonstrates to the reader your level of professionalism. First of all, you need to provide all of your contact information. This includes an email address. Next give your novel a one-paragraph sales pitch. You've got very few words in which to grab their interest, so use those words sparingly and effectively. Next, describe your target market. "Hot Babes in Halters is a story that will appeal to same feminist crowd that made "Brittany's Bio" a best-seller." In the third paragraph, highlight your publishing credits. Here is where the unpublished author is at a disadvantage. Leaving this part out is a flashing banner that screams UNPUBLISHED WRITER!! Yet we all know great novels were the result of many writers' first efforts. You might very well be the next one of those writers. Still, it is best to have something to put here. Submit to your weekly newspaper. Contribute to small publishers, even if they are non-paying markets. Get some sort of credit. But don't lie!
Writing a two-page synopsis of a 600-page novel is one of the most excruciating chores a writer will ever face. But it can be done. Generally, editors and agents want a simply telling of the story from beginning to end. Write it in present tense and don't hold out on the ending because "you don't want to spoil the surprise". The surprise for you will be an instant rejection.
When they ask for sample chapters, they generally want the first three chapters. All they're interested in at this point is whether or not they feel you've hooked the reader (in this case, the editor or agent) into reading the remainder of the book. They don't want your favorite chapters, and unless they tell you otherwise, they don't want your first and last chapters plus one randomly picked from the middle. I have, however, seen editors who DO request first last and middle, but they are the exception and not the rule.
If this material fits nicely into a 10x12 envelope, that's how you want to send it. Do NOT bind your pages and do not use fancy typefaces. Make sure you provide an self-addressed stamped envelope for their reply. If you want your materials returned, then make sure it's an envelop of the same size with the same amount of postage. However, as cheaply as you can buy paper these days, it most likely costs far less to print another submission package than it does to pay the return postage on all that material. I generally provide a #10 SASE and a gentle reminder that recycling paper keeps everybody's costs down and saves a bunch of trees.