Greg Makniw has out some great advice together for aspiring economists. He gives advice to undergrads
here. As expected, it's all right on target. I've summarized it here, with my comments following in italics :
- Take a lot of math and stat courses
- Choose your economics courses from professors who are passionate about the field and care about teaching.
- Use your summers to experience economics from different perspectives.
- Read economics for fun in your spare time. To get you started, here is a list of recommended readings.
- Follow economics news. The best weekly is The Economist. The best daily is the Wall Street Journal.
- If you are at a research university, attend the economic research seminars at your school about once a week.
I'll just make a few additional comments:
- For math and states, try to take at least calculus (derivatives are everywhere in economics, and you'll find your share of integrals too), linear algebra (used often in econometrics) and real analysis (gets you used to doing proofs)
- Spending time around passionate teachers is a good way to ramp up your own enthusiasm (particularly if they're good teachers)
- The remaining suggestions boil down to "immerse yourself in your field." If you want to be an economist (or a finance person, or whatever), spend as much time either doing it or reading it as you can.
He also has some excellent advice for graduate students
here. In this case, however, he's outsourced the task and provided some pointers to others' suggestions. Make sure to read the comments - quite a few people have pitched in with further suggestions.