The Writer’s Market is a huge volume published annually that lists book and magazine publishers, how to contact them, editorial guidelines and most important – what they are looking for. You can browse through certain subject areas and under that publishing company read what they are looking for. This way, you can spot trends and get a better idea of what the public is looking for. This will give you a better idea when judging your book project before you start.
This is also a good source for a list of book categories to research further. The publishers will also list recently published titles which can be another valuable indicator if you are headed in the right direction. Besides all of this, it is a must have source if you are considering having another publishing company publish your book and are not interested in self-publishing. All of the names, addresses, guidelines and everything are there at your disposal including advice, tips, etc.