School will be back in session in a couple of months so I thought I'd give some early advice on picking classes for the new semester. This is the same advice I gave to my younger brother who will be a freshman at Harvard this fall and to all of my students.
1. Psychology- This is by far the most important one. Not only will you have a better understanding of how others think and behave, you will have a deeper understanding of the inner workings of your own mind. I enjoy almost every subfield of psychology (developmental, abnormal, humanistic, analytical) but the most important ones for the average person to know are social, cognitive, and evolutionary psychology.
2. Economics- You don't have to know it at a highly advanced mathematical level. Knowing the essential concepts will suffice: supply, demand, market equilibrium, taxes, diminishing marginal returns, unemployment, GDP, Keynesianism, et cetera. Two semesters that cover micro and macro should be more than enough.
3. Statistics- All the sciences use large sums of data that need to be analyzed through statistical methods. In addition, having a strong grasp of statistics can help you make better decisions in moments of high uncertainty. It may not come easily to some of you, but it is worth knowing well.
An excellent book that touches upon the importance of each of these subjects is Thinking: Fast and Slow by Daniel Kahneman, the 2002 Nobel laureate in economics for co-founding behavioral economics with Amos Tversky. Kahneman is a top authority among social scientists, in the same league as John Maynard Keynes, B. F. Skinner, Jean Piaget, Jürgen Habermas, and Noam Chomsky.
(Optional) Computer Science- We live in an era full of computers and their ubiquity will only increase as time goes by. Unfortunately, most people don't know what computers are or how they work. They use the Internet, but what is the Internet exactly? Is it a really just a series of tubes? Eventually, you will need to know some basics of computer science as they start merging with our bodies and perceptions of reality. (If you have no idea what I'm talking about, look up The Singularity is Near: When Humans Transcend Biology by Raymond Kurzweil.)