is a very tricky thing. In order to sell your work, you have to make sure the market has a place for it. In order to find this out, you can do things like..
Read the Writer’s Market: This will tell you which agents and publishers are representing or looking to represent your genre of writing.
Educate yourself on the Latest Sales: Research the agent or publisher you wish to represent you and see what they have been selling lately. Read bestseller lists on Amazon, the New York Times, etc.
Look on Bookshelves: To notice if you see a trend. We all saw the rows and rows of paranormal romance filling shelves after Twilight blew up, and the same thing happens whenever there is a trend in the marketplace.
The thing to beware of is falling into the trend as it begins to die.
Eventually publishers and agents get sick of seeing the same kind of book come across their desks time and time again with no noticeable differences from books they have already sold. They don’t want to sell a repeat!
For this reason, it is very important not to force yourself to write a book similar to Twilight, for example, just because Twilight was a hit. When it first came out, paranormal romance was not the trend yet. Write the book you want to write, make sure that it fits somewhat into the marketplace by keeping with certain genre must-haves, but be the one to start the trend instead of follow it.
This is why writing for the marketplace is such a slippery slope! On the one hand, you can’t be too different, while on the other you can’t be too similar to books already out there. My suggestion is just to write your story, write the story you love, and worry about selling it later when it is finished. Writing for the marketplace could very well ruin a great story.
Although I personally wouldn’t recommend writing for the market I agree with the closing statement in this. Write what you want to write, not what you think other people want.