Preparing your work properly for the marketplace is of paramount importance. The attachments you send with your manuscript or query will vary greatly depending on the type of project you want to get published.
You may already have a completed manuscript or query you would like to have published, or you may wish to sell an editor on an idea for a manuscript that are normally included with different types of submissions of nonfiction and fiction material.
Magazine Article Idea:
Requires: One page query letter to interest a magazine editor in commissioning you to write an article on a specific subject.
Requires: One-page query letter to interest an editor in reviewing a book proposal.
Requires: Cover letter, overview, outline, author’s information sheet, marketing information, list of competing book titles, and sample chapters.
Requires: Cover letter and completed manuscript
Requires: Cover letter, synopsis, and sample chapters
As you can see, the nature of your work and its state of completion largely determine the materials you need to prepare.
If you don’t yet have a manuscript to sell, you should probably start by promoting your ideas to magazine editors until you get an offer to write an article. If you’ve completed portions of a book manuscript, you might consider sending editors a book proposal that contains sample chapters of your work in progress.