In my opinion,the best user´s guide would be a MozillaZine Forum compilation. As a result, I´ve written the following " sheme " :
CONTENTS
CHAPTER 01
OWNLOADING, INSTALLING AND UPGRADING
1.1.Download Firefox
1.2.Install for first time
1.3.Install from a existing one
1.4.Reinstall Firefox
CHAPTER 02 : GENERAL QUESTIONS
2.1.Differences between Mozilla and Firefox
2.2.Can Firefox coexist with Firefox
2.3.Differences between releases and nightlies
2.4.Differences between trunk and branch
2.5.Where are my personal preferences, bookmarks, passwords stored
2.6.How do I star profile manager
2.7.What is Talkback
CHAPTER 03 : USAGE
3.1.Navigation, Searching, Improving speed and efficiency
3.2.Download Manager
3.3.Customization : Toolbar, Themes and Extensions
3.4.Options
3.5.Controlling Pop-ups
3.6.Managing Cookies
3.7.Keyboard Shortcuts
3.8.Mouse Shortcuts
3.9.Menu Reference
CHAPTER 04 : BOOKMARKS
4.1.How I import bookmarks from others browsers
4.2.How I alphabetize bookmarks
4.3.How I backup my bookmarks
CHAPTER 05 : PLUGINS
5.1.What a plugin is
5.2.How I install Java, Flash, Adobe Reader, etc
CHAPTER 06 : EXTENSIONS
6.1.Where I download them
6.2.How I install from the hard drive
6.3.How I backup my extensions
CHAPTER 07 : PROFILES
7.1.How I access the profile manager
7.2.How I backup my profile manager
7.3.Create a new profile
7.4.Create a new profile without xxxxxxxx.slt
CHAPTER 08 :CONFIGURATION
8.1.The configuration files
8.2.How I edit the configuration files
8.3.The about:plugins,about:buildconfig,about:cache
8.4.The about:config
8.5.How I tweak Firefox for better speed
A correct Firefox User´s guide is a factor because teaches us the huge gulf which exists between Firefox and Internet Explorer