Let me clarify. You have to educate yourself on the language of investing and more importantly, how markets work. The first is relatively easy for the motivated individual. The second requires a significant dedication and study, but the resources are out there either in some classic investment books are researching successful investor's "trading rules." It is my humble opinion that everything you need to know can be found in about 5 or 6 books, but you will have to read them about 5 times each. Even if you master this you still have to master the behavior side of employing any strategy. This is USUALLY the main problem for nearly everybody.
By easy I meant, once you learn the language, it is pretty easy to understand. Buying stocks with low price to book and low price to sales companies is relatively easy as you can screen for them or subscribe to a service.
The third leg is understanding individual markets of each company, which is nearly impossible without some sort of edge, and is exactly where geniuses like Buffett earn their keep. The fourth leg is having a semi-correct macro view. Good companies can overcome this somewhat but the best investors have a track record of picking every single one on the correct side.