I read lots of stuff b/c I bought into the psycho crazies on the pre-law boards. None of it was anywhere near useful. I promise you, there is not a massive conspiracy against pre-law people by law students. We really learned, very quickly, that nothing you do "in preparation" for law school makes a lick of difference. Your professors will focus on certain things that are important to them that you simply have no way of knowing about until you set foot in their classroom.
My advice for prepping? If you want to prep, read a lot of books. Any topic will do. If you're just curious about what you would learn in 1L, read Law 101. But just read a lot. Read biographies about lawyers or major legal cases if you want to. I think it also helps to read the newspaper. You'll learn about current criminal and civil court cases and get a feel for different types of crimes and civil wrongs.
Other advice for prepping? Figure out why you want that law degree. So many students come here not knowing WHY they are here. Take some time to research careers in law, and do some cold calling around to lawyers in your area for informational interviews. They can give you advice about law school, the working world, the areas of law you might want to work in, etc. You can also research firms or organizations you might want to intern with. What are their req's for 1L and 2L associates? When can you apply? How can you work on developing contacts. Develop a spreadsheet. When school starts, you will have no free time to do this and you will be a better position than many of your peers to send out resumes after Dec finals.
If you're still in college, join the trial team or pre-law society. You may get to network with some lawyers. If you have some time to work, get a part time job at a law firm.
That's my prepping advice. It is less to do with being in the classroom and more looking toward the big picture of why you are committing to law school for 3 years.