I learned over a long of time -- before there was an emacs lisp manual. I used Guy Steel's book on Common Lisp as a basic guide to lisp. I would not use it today though. It is nice because you have all the source available. So, just like doing html pages is often the process of find a page that does what you want to do and see how they did it, elisp is the same: find something that is close, understand how it works, then modify it.
So, basically, I would start small, do tweeks and adjustments to existing things. Then move on to bigger things. I generally write most of my stuff in the *scratch* buffer so I can experiment and play quickly. There is another mode that can be used but I never learned it.
Low cost SATA Disk Systems for IBMs p5, pSeries, and RS/6000 AIX systems