One way to write a good user manual is to keep track of the questions people ask when they are trying to use it and make sure they are in the manual. The hard part is making sure people ask questions. You should make it as easy for them as possible, providing a help desk, a mailing list, a wiki, and other forums. But you also need to have someone who periodically scans the help desk logs,
the mailing list archives, or the wiki itself for questions that should be in the documentation.
For example, I just installed an EtherFast? Cable/DSL Router at home. It had fairly good instructions, though I ran into a problem because it was assuming
that my computer was using DHCP and I was using manually assigned IP addresses. The first problem on the Common Problems list was making sure that your computer could talk to the router; either give it a particular fixed IP address or use DHCP. I would have saved half an hour if they had put one sentence in the main instructions to the effect of "If you are not using DHCP, see problem 1 on page 20".
At least they had it in the manual.
-RalphJohnsonFaqAsDocumentation has similar content. -- OleAndersenSee:DocumentationPatternsCategoryDocumentation