If you could go back in time to when you started your undergraduate degree, what would you tell yourself?

Hi Hi! I'm about to start university as a joint Maths and Computer Science major, so I figured I'd ask for advice here on what you'd do differently if you could redo your undergrad degree. Tentatively, I plan to pursue a graduate education in Maths, so I wanna know what I should be doing to kill it in my bachelor's. Thanks in advance!