To get the most out of your college years, make sure you…
Take a course with a professor who makes learning fun. Ask an older student for recommendations here, and give it a try, even if that class is outside what you think of as your own area of interest.
Work with professors who care about students personally. When you find a professor like that, stay in touch, take another class.
Find a mentor. This can be a professor, a post-doc, a grad student, or an administrator, but find someone who takes an interest in your academic journey, and who can help guide your next steps.
Work on a project across multiple semesters. Be able to describe not only what the project was about, but also your specific contribution to the project as a whole.
Find an internship where you can apply your classroom learning in a real world situation. Be able to describe your job responsibilities and how those tied in with your classwork.
Be active in the extracurricular activities on your campus or in your community. College is not all about academic work, but also about the relationships that you are building along the way.