It's very common when you see budding authors scrambling to get their material out, to see them fail. Just like starting a band, or starting a home business, many fail upon genesis because the people involved have no sense of marketing. You could be the greatest novelist the world has ever seen, but without a skill in marketing no one will be exposed to your material. I myself am learning from this right now, and I am looking to tweak my approach in ways I would have never thought about since discovering this process as a necessary precursor to publishing. Here I will give you the gist of my secret, and it is my hope that you leverage this to make yourself successful in the publishing game.
Establishing the Market Demographic
Who will read your book?
First big question here is who will read your book? Generally this step is both the most challenging as well as the easiest step. Here's why: It's easy (probably) to determine by the content of your book what age your book will appeal to the most, however you will find that particular cultures within that age range will be finicky on who reads what.
For example. Say you are publishing a science fiction book, that has a sex scene written into it and some scenes of graphic violence depicted. It's probably a given that the book will be 18+, but 18-65 is a huge range to work with. If the book is a coming of age book then it'll most likely be an 18-25 range. If the main character is male or female, this will change the target demographic of your audience as well. Also, if it is highly philosophical, with a balanced cast of players you might appeal more to 25-45 as far as the age range goes.
Another interesting example is the Jesus Storybook Bible. If you've ever seen it, the cover jacket screams, "this is for children 3-7" because of the art illustrations. However, unchurched converts without any exposure to the book also buy it, in droves! It's extremely popular, something that the publisher would have never figured. You'll find yourself feeling like Tobias on Arrested Development when he finds out his book is suddenly famous, though, unbeknownst to him, only in the gay community.
When will it be most likely read?
Time of the publishing date is incredibly important and here's why: it will greatly increase the likelihood of people to purchase your book. So explain what I mean, here is another anecdote.
A friend of mine is a publisher at EA games who once told my designer for my book, Spirit of Orn, that when Dead Space 3 comes out, it will be in the coming month of February. Back in the holidays I was stunned to hear this. During the peak gift giving season why would you delay your product until after the prime purchase season has passed? Here's why. The market for gaming during the holidays is very specific. During this time game consoles and casual gaming games soar through the roof because all the grandmas out buying the games for their children's children, see a nice caricature of an Italian plumber tearing ass on a race track and think that it's very lovely. They wouldn't see a man ripping a space mutated zombie in half and say, "my that's lovely." No, they would be horrified. That's why most mature gaming AAA titles are released after the fact.
Therefore I suggest looking into the market purchase statistics for your particular genre. Are big scifi releases coming out in May? June? March? Pay attention to this, otherwise you will have a dismal release date. Here it's all about momentum. Run with it!
Each of these I would heavily consider before publishing a book. Knowing who will read your book and what time of year those people are buying is critical to a book's success It also goes without saying that you must have exposure with these demographics prior to the release, otherwise no one will know who you are. That's for another day. Take these two ideas and go with it. Like always, feel free to as me any questions should you have them.