Most importantly, your grades lie almost entirely with your final exams. And your grades determine your employment possibilities.
I've heard people advise rising 1L's to take the summer off; relax because law school is one heckuva three years. Extremely bad advice. Many of your peers (especially those who will do well), are thinking about what it will take to succeed. The grading curve is tight and the difference between "A"s and "C+"s is often hard to discern.
So, begin your prep now. Take it as seriously as you did LSAT prep. My preference, of course, would be that you read my book. But biases aside, it does provide you with a methodology and a way of thinking about the law school process. If you read it and internalize half of its substance, you will be able to "hit the ground running" that critical first year.
Feel free to contact me through this site, if you have any questions. I wish you much success in your studies and legal career.