Importance of Editorial Tip Sheets
Just because you regularly read the books in a particular series, doesn't mean you shouldn't also read the publisher's editorial tip sheets. For starters, you'll need to know how the publisher wants to receive submissions for that line. Perhaps even more important, you'll need to know if the editors are looking for a change in direction for the line.
Most publishers will have copies of their editorial guidelines posted on their Web site under a section called “Submission Guidelines.” If you don't have Internet access, you can usually obtain a hard copy by mailing a stamped, self-addressed envelope to the publisher.
The editorial guidelines often give you additional insight that you might not get from reading the books. Interpreting the tip sheets, however can sometimes be a challenge.
Assume for a moment that the editorial guidelines for the Happily Ever After romance line at Big-Time Romance Publisher states the following:
What does the tip sheet tell you? Quite a lot, actually. First, it offers specific information about the line, such as the word count and manuscript submission procedures. Second, it offers general information about the tone of the novels in the line, which is information you should bear in mind while reading the books.
Think of the editorial tip sheets as general guidelines when it comes to things such as story content and tone. Always read the novels published by a specific imprint to get a general feel for the books, rather than rely solely upon the tip sheets.
Sometimes the editorial tip sheets don't give a complete overview of the line, especially for what the publisher expects from a new author. To obtain this information, you'll need to read a sampling of the books. A good rule of thumb when choosing books to read for researching a line is to read all their releases within the last two months. Make a note of which selections were from new authors since that will give you a clearer idea of the type of new projects that work for the publisher in this line.
Assume that you have read all eight of the Happily Ever After romances released for the past two months. Of those books, three were from new authors, four were from authors who've sold two or more titles to the line, and one was from an author considered to be the line's top seller. Observe the tone of the four books written by the line's existing authors but pay close attention to the storyline in the three titles from new authors. How do those books differ from the others in the line? How are they the same?
Answering these questions correctly is often the key to selling your romance novel to the targeted publisher's line.

