If you intend to branch out from psychology in your career or graduate studies, you should take some undergraduate courses in the field you intend to pursue. This is particularly important if you intend to find work without getting a graduate degree. For example, you might be hired to work in marketing research. What you have learned about research methods and human motivation can be very relevant, but your chances at such a job are best if you have taken some business courses.

Graduate programs in psychology are very much about research. You are encouraged to do independent research, even during your first year. This helps teach you important skills you need to know to work in this field. It gives you ideas for your thesis and dissertation research, to come later. And, if you can get your results published, it adds to your resume.