This article is from the misc.writing Writing FAQ, by Wendy Chatley Green email@example.com with numerous contributions by others.
Research the rules of the market you're submitting
to. For short fiction (less than 20,000 words), you
normally submit the entire manuscript. For novel-length
fiction, many publishers prefer to receive a couple of
sample chapters and an outline; if the publisher likes your
sample, he/she will request the remainder of the book.
Publishers won't normally commit to buying a
manuscript from an unknown writer until they've seen the
whole thing. DON'T submit a portion of an unfinished book,
unless you are certain that you can finish the book very
quickly (within a month) if the publisher expresses