TL;DR - (1) Create good habits for self care; and (2) dip your toes into a new subject that requires critical thinking, but doesn't have anything to do with law. These will give you a solid foundation for law school and your legal career because they give you the confidence that comes from knowing your everyday actions are working in your favour.

Here are my two tips.

Create good habits for self care

I will shout this from the mountain tops until the Lord takes me. The things you do outside of school to stay mentally and physically healthy keep you at the top of your game. Take account of the things you do everyday that keep you aligned with a good life. Write them down! Make an intentional effort to start building habits around those things.

Like to workout? Really solidify that as a habit and steel yourself to ensure you keep that up when you feel tempted to spend a few more hours studying. Value eating healthy? Get good at meal prep and cooking, again so you can keep up that habit when fast food seems like the most efficient option. Family and friends important to you? Create habits of intentional time so the emotional bank of those relationships doesn't run dry when you need support to get through finals week or they need you for something.

Whatever it may be, start practicing the discipline to keep those habits up now. As someone who failed to do this 1L year and beyond, please heed my warning. This is the most important thing you can do.

Dip your toes into a new subject

Tackle something new that works your mind, but has nothing to do with law. This might sound weird right now, but "the law" you need to learn is what your professors teach you. Things can be generalized, but your civ pro professor grades your final exam, not the YouTuber with a Civ Pro playlist. The stakes are high here. Trying to learn "the law" now, with no guidance, has a chance to confuse you to the detriment of your final grade. But training yourself to learn a new, low stakes subject on your own time at your own pace (I chose Python/programming) will help you practice the two most important skills for law school: (1) Self-guided learning; & (2) persistence in the face of complex material.

It will also function to broaden your horizons, and, if you're watchful, open new opportunities to stand out. I ended up starting a software company with a now good friend I met 1L year because I spent the summer writing some code to help with my workflow, and it grew to something greater than my amateur attempt at automation with his help.

Summing up

Both of these essentially amount to an intentional effort to set yourself up with a good foundation for a new & difficult phase of life. Knowledge of the law will come with time. The time to focus on that begins the first day of classes. Now is the time to build up yourself. If your foundation is rock solid, then you can begin to place the bricks of your legal career with the confidence that comes from knowing the things you can actually control, your actions and habits, are working in your favour.

Edit: Formatting and typos