Researching what publishers want is a good idea, but to improve the chances of getting published it's also a good idea to research publishers individually. Sending out submissions to every publisher with a listed address is usually a waste of time. Publishers receive hundreds of submissions, many do not even accept unsolicited submissions. That means that submissions have to come to them through a literary agent. Look at each publisher individually, find out if they accept unsolicited submissions, what kind of books they publish and, if possible, what kind of books they are looking for.
Either before or after researching publishers, research readers. Ultimately publishers are in the business of selling books, which means that publishers are looking for what readers are looking for. Find books that are similar to the type of book you hope to get published and find out how well they sold. Knowing as much as possible about the audience for a book, who the readers will be and how many copies they might buy will impress publishers and help with their decision making.
Bookstores are in the business of selling books to people, publishers are in the business of selling books to bookstores and distributors and agents are in the business of selling books to publishers. It is unlikely that an agent will take on an unpublished author unless they have made a name for themselves elsewhere, but it's a good idea to consider submitting a book to agencies as well as publishers. Come up with a short sales pitch for the book. This should include what the book is about, what genre it falls into, who the audience is for it and information on the sales of similar books.
Most publishers do not want a copy of an entire manuscript. On the website of publishers, those that accept unsolicited manuscripts will usually say what they are looking for. Most of the time they will ask for a cover letter, a synopsis or a few sample chapters and a self addressed stamped envelope. Include the sales pitch, mentioned above, in a cover letter and submit only what is asked for. Be patient, the response may take awhile, but don't submit to only a single publisher and then wait. After doing careful research begin submitting to several publishers and, if applicable, agencies.