Decide on a research topic. If you are writing an academic thesis, pick a topic that interests you and that you got good marks in as an undergrad. If you are writing a popular book, pick a topic that interests you and is likely to succeed with a popular audience. If you don't know what social behavior topics audiences are reading about, pick up a copy of a science or social science magazine, and take a look at the letters to the editor.
Gather research materials. For academic papers in sociology or psychology, go with books and academic journal articles. Use academic searches like JSTOR and Academic Search premier to find the best materials on your topic. For popular books, use academic reference materials, but also consider interviewing subject matter experts at colleges and universities. To find such experts, look them up and contact them at their office email address or phone number.
Take notes on your research materials. Read each book and article, making a rough, bullet-point outline of the main argument in each. Copy quotes and page numbers for ideas that are crucial to the main argument. Photocopy tables, graphs and charts that contain vital statistical information.
Write an outline. Decide your approach or angle based on your readings, research and (if applicable) interviews. Break your ideas down into parts, and designate a chapter for each part. For example, if your book is about why social forces influence people more than logic does, you might include a chapter on social conformity, a chapter on media influence and a chapter on fashion trends. Under each chapter, write a series of bullet points on which statistics you will use, which authors you will quote and which case studies you will cite.
Write an abstract or introduction. If you are writing an academic thesis, type up one paragraph outlining the basic arguments you will make. Do not describe each chapter in detail; instead, write a bit of background information on your topic, a few sentences summarizing your research and one or two sentences that cover the basic thrust of your argument or idea. If you are writing a popular book, write an introduction of several pages that tells the reader why the topic is important, how your book will address the topic and what the reader can expect in the coming chapters.
Write each chapter in order. Cover all the arguments, statistics, case studies and quotations you included in each chapter outline. For each new argument idea, write a paragraph or two to state the argument, followed by a few paragraphs backing up the idea with statistics, case studies and research citations. Do not simply throw statistical information out on the page; build a bridge between your ideas and your research by logically explaining how the data leads to the conclusion.
Edit and proofread your book. Read the book over two or three times yourself to see whether you are happy with it. If you are unhappy with any of the content, remove or replace the sections you do not like. Hire an editor to review your manuscript for grammar, spelling and content. Pick an editor who is experienced, and who is willing to send you a sample of their work. Many editors can be found online. Contact several editors, ask them about their rates and hire the one who offers the best combination of price and quality.