I am pretty sure a lot of people, myself included, learned things by actively messing with it. Books are helpful for basic, but for everything else, just installed a Linux distro (I like Debian!) and then proceed to play with it. Read a few online articles (http://www.google.com/search?hl=en&source=hp&biw=141...) and just build your experience slowly. I use VirtualBox (http://www.virtualbox.org/) to install Debian on my Mac/Win boxes.

Good luck and as always there's #apache on freenode.