There are several things that you can do to prepare yourself for the LSAT. The Fall of your Junior year is a good time to start preparing.
Download a copy of the LSAT/LSDAS Registration and Information Book and read it cover to cover.
The best preparation is to take real LSATs under simulated conditions. Take as many of the old exams as possible and time yourself. Sample exams can be purchased at lsac.org for $8.00 each or in commercial bookstores such as Barnes & Nobles. Among the least expensive preparatory materials is the LSAT: TriplePrep Plus with Explanations, distributed by the LSAC. The Valpo Pre-Law Society holds two or three practice exams every year. Start taking practice exams early in your junior year. Figure out if you are weak on a particular section of the exam so that you can focus your preparation.
Study guides can be purchased in most good bookstores. These are not as helpful as taking the actual exams, but they can provide you with additional vocabulary and questions to work on. The best commercial study guides are probably published by Nova, Kaplan, and Princeton Review.
Many students take an LSAT prep course. Some students swear by these courses; others do not find them helpful. Most courses are very expenses. Realize that there are no secrets about the LSAT. The format and general balance of questions is the same every exam. If you are a self–disciplined kind of person and you invest in some sample exams and prep books, then a prep course might not be worth the money. On the other hand, sometimes the very fact that you have spent a lot of money on a prep course will make you take the whole process much more seriously.
Take Logic and Critical Thinking (PHL 100). Your homework assignments and exams in this class will look a lot like the LSAT.
It is important that you be prepared to succeed on your first attempt at the LSAT. You can retake the test, but remember that most law schools look at the average for every time you took the LSAT.