In my experience learning what you need to know is a combination of a couple of things.
First off, you need to have a helpful forum like this one to ask any questions that you have or come across. You also can learn a lot from doing searches on Google, Bing, Yahoo, etc. and reading blog posts and articles about the topics that you are seeking information on.
As for eBooks, from my personal experience the majority have no special information that you can't find on Google or the other SE's. A lot of eBooks are either trying to get you to buy their product/service at some point in the eBook. Also, many eBooks have dated information that might not be accurate or relevant. Many are so called "Updated" or "Revised", but it's still either dated or info you can find reading around the web.
My suggestion is to spend as much time searching and reading as you can. When you have questions or can't find information that you need then post a thread here and someone will surely help answer your questions.
Take a look around the different forum categories here and just read all you can. You will be surprised at how much you can learn by just browsing through our many forum sections.
