Why this is a mistake: Like any other business, publishing is fluid. Things change. I’ve seen authors and even agents get left behind in the business as the marketplace, technology, and even consumer tastes changed. Too often writers work off of out-of-date templates. A magazine writer, for example, has to see what a magazine wants now, not what it wanted a year ago, and, actually, what the trend for the future is, as the magazine is actually buying a half-year to a year out. Publishers are buying books that they will be publishing years into the future.
While I noted elsewhere that you shouldn’t necessarily write to the current market and you can’t predict the future market, you should still stay abreast of the market and the business.
The solution: Stay informed. Subscribe to free e-newsletters like the one from Publishers Lunch (www.publisherslunch.com), and read industry publications like Publishers Weekly. Conferences are also a good way to stay abreast of news inside your particular area of writing. Networking, of course, is important, as noted elsewhere. Online chat groups that are linked to your type of writing can be valuable as well. (See Appendix I in The Mini Market Book for a list of helpful Web sites.)