Summarize:

Writing a book is a significant undertaking that will require a lot of time and energy. Choosing a subject you know and care about will help propel you through the daunting process. Explore your passions and interests when choosing a topic and make sure you have something important to express on the matter. Choose a genre that you love to read and have explored in depth, whether it's horror, romance, or political intrigue. Choose a genre that others will find interesting as well. You'll also find it easiest to write in a genre you're familiar with, since you'll have a good grasp of the common tropes and conventions of the genre. If you're writing non-fiction, make sure that you have a level of expertise and credibility on the subject. You should read other similar books within your genre both before and during your writing process. Read these books with a critical perspective, noting which aspects of the author's style you like and which you would do differently. Doing this will keep you connected to the reader's perspective throughout your writing. It will also keep you aware of what has already been said on the subject so you can produce an original work of your own. Make notes while you read so that you can keep track of your reactions and observations. You might keep a notebook or journal on hand as you read, use sticky notes, or start a document on your computer where you can make notes. The plot of your book will likely change as you go through the writing process. Still, it's good to begin with a rough outline of the major events and points of interest you wish to emphasize. Focus on how your content can be organized to best achieve your book's purpose, whether it's to entertain, inform, or titillate your reader. You can take note of valuable plot sub-points, methods of describing imagery, or how the dialogue is developed. Don't focus too heavily on chronology or dividing the content into chapters with your initial outline. You can consider these aspects before writing but a general plot outline should come first. For non-fiction books, outline the core concepts you are trying to express in the book and fit specific examples and plot devices underneath them as subpoints. There are a lot of different outlining techniques out there, for both fiction and non-fiction. If you're not sure where to start, do a quick online search for "book outline templates." You can also try more specific search terms, like "romance novel outline template." One popular outline style is the Freytag Model, which allows you to diagram the plot structure of a work of fiction. Do an online search for "Freytag Model" or "Freytag's Pyramid" to find templates and resources for making this kind of outline. If you are writing a fiction novel, your characters will be critical to conveying the story. Start by outlining their function in the story, whether they are protagonists, antagonists, neutral, supporting, or ancillary to the main plot. Then develop more specific characteristics pertaining to their function in the story like their personalities. Developing backstories for your characters, even if those stories don't factor into the actual content of the book, will help you conceptualize how they might react to plot points or interact with each other. Try to make your characters realistic so they will be relatable, even if your book does not take place in a realistic setting. If you do have a mythical-type setting, like a world with dragons, try to consider how real people would react in that environment. If you're not writing fiction, then key events may be the major "players" in your book. Spend time early on familiarizing yourself with the major events or concepts that form the core of your book, since this will help you think through your book's organizational scheme.
Choose a subject you're passionate about. Read similar books. Outline your plot or structure. Outline your characters or major events.