I've researched and written a number of factual books and articles. There are many "right" ways to do this. Here's the general plan I follow for a factual book aimed at children.
1. Say the topic is sharks. I go to the Internet and discover all I can about sharks. I don't print everything out—only things that look particularly useful and reliable. If a website doesn't have much useful content, I just make handwritten notes.
2. I go to the library and look for children's books on sharks. (Whether I'm writing for children or adults, I always go to children's books first because they give the basics in a way that's easily grasped.) Then I look at encyclopedias, then books intended for adults. I may not find an adult book devoted entirely to sharks, but may find some on inclusive topics such as fish, fishing, and marine biology. I also look at the library's vertical files (which contain magazine articles and other non-book sources).
3. I take out of the library any relevant materials that I can. In the case of materials that may not be taken out, I make notes and/or photocopy useful pages.
4. When I get home, I make a pot of tea and take stock of what I have. On any pages I've printed out or photocopied, I use a color coding system to highlight information on the various subtopics I plan to write about; for example, the appearance of sharks, where sharks live, what sharks eat, their lifecycle, different types of sharks, human interaction with sharks. I use crayons for color coding because there are more colors and they don't run dry like felt pens. Also crayons aren't smelly like felt pens.
5. For materials that I can't write in, for example, books from the library, I make notes either on the computer or by hand. Many of these notes consist simply of page numbers relating to the various subtopics. For example, I may note that pages 33-45 of the book Large Fish of the Atlantic gives useful information on human interaction with sharks. I color code these notes in the same way as I did the other information.
6. Once I finish all my color coding, I sort my papers according to color. Some have several colors on them. I put these in a pile designated multi-informational sources.
7. Then I start to write the book based on the information I've gathered. As I write I find I need further information here and there. I look for this on the Internet or at the library, or by sending e-mail queries to addresses given on websites, or by phoning relevant people, etc.
8. Once I have a draft I'm fairly happy with, I find suitable experts to read it. When I get feedback from them, I revise accordingly. Then I often run it past them again, just to make sure I have it right.
