University will be hectic, and during the summer, there's many ways to help you prep for the flurry of assignments, tests and exams that head your way.
One of the best things to do is research about your program and courses: what are your first year course requirements? Who are the professors? What is the course structure (are there weekly assignments, labs, tests/quizzes?) There should be a lot of information online, and you can ask around on forums. Understanding your program's expectations is a good way to ensure you're prepped for what's to come.
It's important to keep track of your tasks and schedule. I'd highly recommend using some sort of planning app on your phone (personally I use Google Calendar and Keep) or a physical agenda to keep track of what you need to do, and when certain events are. You can implement this into your everyday life (schedule time out of your day for meals, to exercise, to work on a project, etc.), and it'll help make the transition easier.
Also it'd be great to research the academic resources available at your university. Are there tutors or teaching assistants that you can reach out to? Who do you contact in case you have questions about your program (i.e. your advisors)? What services does the library offer? For example, my university has a "Writing Centre" which offers free and professional review of resumes and cover letters for job-hunting. A lot of this information should be given to you during your first week of classes and can be found online.
Best of luck!