When setting programming for the news or doing layouts for print and online media the saying "If it bleeds, it leads" is sort of a mantra. For those not familiar with this motto it basically just means that whatever is the most dramatic and / or violent that will capture the attention of the viewing audience, that is what you begin with. It is the news version of a hook.
That same idea is used when writing a book. The hook is what draws your readers into the story and hopefully captures their imagination enough to make them want to finish the book. Murder mysteries, thrillers and many dramas will begin with a dead body, a whodunit. By putting that violent scene right up front and asking the reader who could have committed the crime we help make them a part of the story and they get to solve everything right along with the main character.
For romance novels there can be an affair or some kind of an ultimatum stated immediately within the opening pages. Paranormal, fantasy and sci-fi stories usually place the reader into the world the story is set in. It will either start by drawing the reader into their new setting or will put them into a major Battle Royale giving snippets of the setting as the fight plays out. No matter what we do as writers our main job is to get the reader interested when they first open the book. If it bleeds... we shock our readers and make them have to know what happens next.
I am working on several books right now and I knew I wanted to draw the reader in, that is my job as an author. The problem is that I haven't written many books and so haven't had a great deal of practice putting in that shocking and captivating beginning. After reading more, not only as a reader that enjoys taking in new stories but also as a writer to see how those I admire craft their words, I am beginning to see more and more some of the effective ways to create that scene.
I am also working on writing books that have more of a dark side and violence within the pages such as murder mysteries and thrillers. These allow me to showcase that side of writing easier because they are genres I am familiar with and they are based in that more action-packed realm. There is a learning curve to anything and writing is definitely no exception. Having prose that hold the reader and an ending they have to reach are extremely important but you have to bring them in first. You must capture them and make them need to turn the page. Shock them, grab them and bring them to the edge of their seats as they enter the world you created.