Publishers and agents talk about reading widely as a mantra that you might think is just the way to promote their books. Think again.
You need to know about your competition. You need to know if the opening pages of your novel read as good as the leading books in the genre. If you are writing crime, read Louise Doughty, Erin Kelly, Gillian Flynn, S.J. Watson, Nicci French, Paula Hawkins, Sophia Hannah, Thomas Harris and Tana French. If you are writing criminal procedural, read Peter Robinson, Lee Child (although his brother now writes his books). If you are writing horror, read Stephen King and Alex North.
If you are writing romance, read: Nicolás Sparks, Danielle Steel and David Nicolls. If you are writing erotica, read E.L. James. If you read widely, you can see that there are books that might be stylistically less successful and with a common plot structure, but they do much better than those which are very high-concept and evocatively written. This is because it is not the publishers who decide which books are going to be successful, but the readers. You, as a writer, need to be able to spot these trends and use them to your advantage.
Be careful of nevertheless just falling into the trap of the trend and ignoring your own creativity. Although the agents and publishers often claim that they are not looking for new ideas but a new perspective on something that was done before. I think this might not be entirely genuine. There are books that just happened, like ‘Lolita’ by Vladimir Nabokov, and these would be unlikely to be published in the current world of books. But no one likes copycat novels that just regurgitate the same plot. You have to avoid ideas that were done over and over again. You also need to stay away from clichés, which might include writing characters that are already written. You might like Jack Reacher or Hannibal Lecter, but their stories have already been told. Many successful writers acknowledge this state of affairs. For instance, Erin Kelly, when writing ‘Watch Her Fall’ had an idea in her mind to write a book about someone who is bound to her apartment due to mental illness such as agoraphobia, but this was done to the worldwide acclaim by A.J. Finn in ‘The Woman in the Window.’ Similarly, Peter Robinson said that it was suggested to him many times, and even he considered himself to write about a serial killer. However, he is aware that this was well-portrayed in Thomas Harris’ books.
Furthermore, the most successful writers were the readers first. It is very rare for debut crime writer to acknowledge that they read only one crime book in their life. Most of the writers are voracious readers by nature. They are lots of book on how to write, but many of them acknowledge the need to read novels in the first place. You can learn from the best, but if there is a book that the critics didn’t particularly acclaim by still produces large sales, you can learn about the market and readers from this book. There are books that you might find to go through quickly, but you do not remember what they were about. The books on writing and creative writing courses may teach you how to make the reader keep turning pages, but they would not teach you how to make your novel memorable. This thing you can only judge from the books that you have read.