Generally, reading criticisms of other theories will save you a lot of time. It protects you from wasting your time reading those other theories. This site is run the the people who organized the occupy wallstreet protests. There's plenty of criticism. I hear they are coming out with a textbook soon.
I would like to learn more about economics but I don't know where to start. Can lesswrong suggest specific areas of economics that are particularly useful for understanding and optimising the world? Specific suggestions such as reading lists and resources would also be much appreciated.