My friend and colleague Eugene Volokh posts on the question: What Book Should I Read Before Going to Law School?:
Please post your answers here, but for now let me mention mine: A good English usage dictionary ? my favorite is Webster's Dictionary of English Usage, but Garner's A Dictionary of Modern American Usage is good, too. (Garner also has A Dictionary of Modern Legal Usage, which may be worth reading as well, but it covers a different set of matters.)
I offered a somewhat more detailed list in my Corporate Law Canon, which offers the books I think every aspiring corporate lawyer ought to have read.