Publishers are always receiving what are known as “unsolicited manuscripts”. i.e. people randomly submit their work to a publisher in the hope that it might catch their attention. In reality, very few unsolicited manuscripts end up being published.
There could be a host of reasons why, but one very common reason is that the author has not researched the publisher’s particular market niche – and therefore their manuscript was never going to be suitable.
Browsing the web, it’s not hard to discover what type of book a publisher produces.
Do your research and find publishers who are a good fit for your project. Then, in your covering letter, explain why you feel that your project would be a good addition to their list.
Avoid making overblown claims like, “I believe that, given the chance, this will be a guaranteed bestseller…” etc! Just focus on how your work will complement their publishing goals and you stand a good chance of being taken seriously.
Finally, make sure you put together a great proposal (there is plenty of advice available online, but we’ll discuss this more in later posts). A good proposal should answer the questions: What is this book about? Who is it aimed at? What will the reader take away from it? (i.e. is there something that the reader is supposed to do as a result of reading your book, or one key lesson they will learn?)