Explore. Explore like crazy.
- Web development: . Learn the basics of how web applications work. Understand the client-server architecture.
- Mobile app development: . Learn how mobile devices are different from desktop devices. Learn about REST APIs
- Machine Learning: . Learn how Machine Learning algorithms work. Take up simple ML-based projects.
- Cryptography: . Learn how your data is ensured to be secure when it is transmitted across machines.
- Competitive programming: . Learn to build the right programmer attitude.
- Research: (I am not the best research guy).
Basically, explore all avenues of Computer Science and figure out what interests you the most. This way, you can plan your course-work, projects, and internships accordingly. For instance, if you have decided that you want to build a career in Machine Learning, you can aim for an internship at an ML-based company/startup during your 2nd/3rd year summers.