First, explore external and internal cognitive system on one's own initiative. 

Second, follow your heart and make a choice after getting in touch with your thoughts and be with yourself.

Thirdly, the perfect major is what you are good at, what you like and has a great prospect. 

Fourthly, chose a major doesn't means you are limited to this field. There are numerous opportunities outside your major can be seized.

Last, communicating with professors and searching the latest news about your major can helps you understand your major.