Nonfiction can be visualized as existing on a sort of spectrum. On one end, essays, memoir and creative nonfiction nestle close to the more fact-oriented fiction genres. On the other end, reference books and hard science books anchor the genre firmly in reality. You can get an idea of the variety of nonfiction possibilities by thinking about this list, from least to most factual: memoir, essay, autobiography, self-help, biography, history, news, travel piece, instructional, reference and mathematics. The least fact-oriented genres are also the most artistic by far; as readers demand more facts in a piece, they also demand less art.
No matter what end of the spectrum a work lies on, outlining it will be fairly straightforward. While fiction requires rising and falling action within a plot, a nonfiction outline is defined largely by its lack of plot. Instead, the writer is required to determine what the goal of his work is to be, then work out the steps necessary to achieve it.
For example, in a book teaching how to use raw HTML to create a Web page, the writer might introduce the book by talking about the philosophy, history and design of HTML, then continue by writing the book in the order he'd teach a beginner HTML. A history is generally written in sequential order, starting with a birth or the beginning of the primary focus of the book and ending with a death, the focus's ending or simply the present.
A critical skill for nonfiction writing is the ability to research thoroughly and well. Whatever the purpose or genre of your writing, accuracy is key. Consider, for instance, a cookbook, a travel guide and a programming textbook. Without accurate information, each of these nonfiction works is either flawed or useless.
Nonfiction writers must be able to find obscure information and apply it to their own work. While the Internet has made this task infinitely easier, nonfiction writers should be prepared to do research in a good library or simply by picking up a telephone and calling someone who knows a critical fact.
Like fiction, nonfiction has many different genres, and each genre has its own rules. Cookbooks, for instance, use a standardized method for writing recipes. Travel guides deliver information about hotels and specific locations that a history set in the same area would leave out.
While the skill set for writing nonfiction works is similar throughout the field, the specific genre rules can be difficult to learn. A wise nonfiction writer will focus on a single genre, master it and then expand to similar ones.
If you want to be a nonfiction writer, your best bet is to find some fact in your genre that no one has written about yet and write about it. While the more fact-based genres are more likely to require credentials, you are often able to break in without them if you research your facts well and present a new perspective through your writing.
Start small. Write articles about your chosen area of specialty. Place or sell them online. Send queries to print magazines that might like your nonfiction work; see if they'll commission articles. Save all your articles and think about ways you can put them together in a portfolio.
A nonfiction writer, unlike a fiction writer, can often get an advance from publishers based on a proposal, not a written book, even if she's never published a book before. However, a nonfiction writer must have promising professional credentials or a good body of published work in her book's topic area.
When you have a decent body of work in print magazines or well-established online venues, look for an agent. A good agent for nonfiction writers can help you put together a book proposal and sell it to a publisher. Once you've sold that book, your future in nonfiction publication depends entirely on its performance in the market. The better it sells, the easier it will be to get your next books published.