Study math. Having good math skills is essential to being able to study economics. Other subjects such as history, philosophy, business and politics are useful, but without math abilities you will not be able to study economics.
Apply to study at colleges respected for their economic prowess. Harvard University, the Massachusetts Institute of Technology, Princeton University and the University of Chicago all have highly influential economics departments. Outside the U.S., the London School of Economics is another institution worth looking into.
Learn about the dominant theories in economics. Most experts subscribe either to the loosely-regulated market model advocated by Milton Friedman and his followers (the so-called "Chicago School"), or a more centralized approach supported by the likes of John Maynard Keynes. Analyze the differences between the competing theories and formulate your own opinions.
Follow economic developments in the newspapers. Barely a day passes without a decision being made by the U.S Treasury Department or similar body abroad. Consider how these decisions impact your local area and the people you know.