This will be my last writing post until after the holidays because I want to take a little recharging break. I will be taking ideas or questions for future topics, though.
One bit of advice aspiring writers are given is to study the market by reading a lot of the kind of books they want to write. The question is, what should you look for, and what do you do with this information?
The answer is that it varies, depending on what you're trying to write. One area where market research is essential is category romance, such as the books published by Harlequin. They have defined lines that are distinguished by length, tone, degree of "heat" and other elements. If you want to target one of these lines, you need to get a really good sense of what they're publishing, and that goes beyond the guidelines they issue. By reading a lot of these books, you'll get a sense of what kinds of characters and settings they seem to like and what plotlines are overused or possibly desired. If every other book is about a cowboy hero, then that generally means they really like cowboys. This is one area of publishing where writing specifically for a particular line is a good idea. There's not much else you can do with that kind of book, so it makes sense to be very targeted to what they seem to be publishing.
In other kinds of publishing, researching the market is more to give you a general sense of things rather than telling you what to write. If you read a lot of what's been published recently, you can start to learn the cliches that might be overused and you'll know how original your story really is. You can get a better idea of what publisher might be a good fit for you, based on the general kinds of things they publish. In that area, look more for style or tone than plot because most publishers don't want to have two authors doing really similar stories. But you can tell if a particular editor or publisher seems more in favor of dark and angsty vs. light and fun, for example. Sometimes authors mention their agents and editors in the acknowledgements of a book, so you can make a list of people you think might be interested in your work.
One thing you shouldn't do is chase the market. Most books hitting the shelves today were probably bought about a year ago and may have been written a year before that. By the time you get a book written and submitted, things are likely to have changed. Angsty shapeshifters may be the hot thing now, but by the time you go and write a book about an angsty shapeshifter, the publishers may have had their fill. However, if you've written a book about an angsty shapeshifter, you'll know you need to strike while the iron's hot, and a publisher that hasn't done one yet but that seems to publish books with your style of writing might be a really good target.
What if you can't find anything like your book? That doesn't mean you should give up, but you need to be aware that you might have an uphill battle -- and if it does sell, you could possibly start the next trend. If you're not writing what's currently hot, you need to make that book brilliant and so enthralling that editors can't put it down. Theoretically, every submission should be that way, but the "hot" trends are an easier sell, either to an editor or within the publisher (because even if an editor likes it, she has to get buy-in from the people who hold the purse strings). You can also look for books that have elements in common with yours, even if there's nothing exactly like it. Do you have a similar writing style or tone to something else in your genre? Is your main character similar to a main character in a published book? Are there plot elements that might appeal to the same people?
When I set out to write something new, I try to read as much as I can along those lines, whether it's setting, subject matter, plot, time period or even style. That gives me a sense of what I like and don't like in that kind of book and helps me be sure that I'm being moderately original rather than accidentally duplicating something that's already out there. I can sometimes find patterns of what seems to work best, and I get ideas from twisting existing tropes. Then when it's time to submit, I can give my agent a list of comparable titles that she can use when pitching my book, or that list helps her narrow down her plan of where to submit.