When it comes to investment education, the very first book I would recommend is the "Intelligent Investor" by Benjamin Graham. This book is also referred to as the layman's version of "Security Analysis" by Doud and Graham.
Security Analysis is a much more rigorous book regarding the details of economics, portfolio construction, accounting and finance for investment management. It also is a great book, but requires patience and tenacity to work through the entire book. Thus, the "Intelligent Investor" provides an easier explanation and application of the tenants of value investing.
Value investing often appeals to many because of its logic and simplified approach. A good example is buying any good. You buy stocks when the prices are favorable - "on sale" and don't buy when prices are at high levels. Buffett, who is the most well-known of the value investors, says that you should buy your stocks like you buy your groceries. You're not likely buying eggs if a dozen costs you $20. Oddly enough, people do that when they buy their stocks.
Another of the many aspects of value investing is the "margin of safety" concept. Basically, you are always cognizant of your downside risk.
In corporate finance, many private equity (PE) firms boost their leverage to a high degree, for example 95%. Suppose the business has small margins. This means that anything that disrupts the business's financial income could have dire effects upon the company. Toys R Us is a perfect example. They were highly leveraged by the PE firms that bought them just as they were being pressured by their competitors and the results were a disaster.
If a value investor was in charge of the capital structure of the Toys R Us, the value investor would have acknowledged this extreme risk by leveraging the business at lower than industry rates. This creates breathing room, if you will. That is exactly what the "margin of safety" represents.
There are many other concepts the reader will gain from reading what I consider one of the most important investment finance books there is.
Graham's teachings were behind the codification of investment analysis into a profession. Prior to this book’s methods, the basis many investors used for purchasing investments was all over the map. It often didn't have any basis in the finance, accounting, or economics of the security’s fundamental business.
This book in conjunction with the establishment of the Financial Analyst Federation (FAF) was the beginning of "the profession" of securities analysis. The FAF was the predecessor of the current day CFA society.
This is a must read book if you really desire to improve your investment returns. The educational journey to be successful in investments is not any easy one, but otherwise you give up much better returns when you layoff the responsibility to others.