@gibberade - Totally depends on what you want to invest in, obviously ;-)
Man, Economy, State by Rothbard is a good place to start. It's not really an investment book. Rather it's an economics book which will teach you more about economics than most economics books.
Possibly due to my background I think bottom-up/a priori is the best way to go. In other words, I believe that macroeconomcs can be understood through an understanding of microeconomics with appropriate structures.
As with everything else ... get the fundamentals correct (for stocks, that financial statement analysis). Then realize that the structures could be almost anything.
A popular method is comparing P/E and drawing conclusions based on that by discount the number into the future and adding a growth rate. It's almost completely arbitrary.
Assume E=$1. Assume earnings growth is 10%. Also assume your discount rate (the return you want per year is 12% ... say 6% plus 6% risk). Also assume that you figure (for whatever reason) that the market will pay a P/E=20 for it... why? No reason other than this is popular for growth stocks. Also let's assume you'll hold it for 5 years. What is the stock worth?
Suppose it's currently trading at $16. Should you buy it? Well, maybe you want a 50% fudge factor... you'll only buy at 18.27/2 .. under $10.
It really can be this simple. Now to some this looks very clever, but if you start playing around with the numbers, you'll see how much the numbers depend on the input.
This just shows the valuation as a growth stock. You can also evaluate it using discounted cash flow or enterprise value (including the debt but excluding cash) / top line earnings--- this would be the value if you bought it outright off the market as a private equity person.
Whenever analyst companies give predictions about what a stock should trade at next year, they're not doing anything much more complicated than that. The art is in inputting the right numbers in the very simple equations.
The hardest part about of investing is probably realizing that there's nothing more to it than that. You'd expect some kind of super equation, but it isn't there. Everything in the equity market is similar in complication to this right up to the CAPM model which you can handle with high school math.
(The heavy math is found in the derivatives markets.)
Hence the technical part is really quite trivial. Basic algebra. The hard part is in relating those numbers to the real world. This is why the best investors seem to read a ton.
In reality the market is then a combination of different players using different models because they have different goals. As you probably know, some market players make no use of any models whatsoever.