The LSAT/LSDAS Registration and Information Book is a comprehensive guide to the law school application process. Published by the Law School Admission Council, it contains the application for the Law School Admission Test, as well as other forms you'll need if you decide to apply to law school. Free copies are available from Career Development or from Cheryl Mathes, 213 Campus Center. Also, pick up the supplemental booklet containing a sample LSAT (also free). Both items are also available from Law School Admission Services (215-968-1001).
To apply to law school, you must take the LSAT. The application and instructions are in the Registration and Information Book.
You should take either the October test or, at the latest, the December test. For instructions and sign-up forms, consult the LSAT/LSDAS Registration and Information Book.
Should you cancel your test score? If you have just taken the LSAT and have a sickening feeling that you screwed up, you do have (for a very short time) the right to cancel the score so that no one will know how you did. You can cancel your score while you're still at the test center - but I strongly urge you not to take that route. That's the worst time to make a decision and it can only help to have a few days to make your mind up. I recommend that you use the other alternative: Law Services must receive a mailgram, telegram, fax, or overnight letter from you no later than five working days after the test date. (See page 13 of the Registration and Information Book.)
Should you retake the LSAT if you're disappointed by your score? If you were sick or overly nervous when you took the test, and if you honestly feel confident that you can increase your score by ten points or more, then consider retaking the test. But if you already gave it your best shot, why go through that misery again? If you want to, feel free to talk with me before signing up to retake the LSAT. There are other factors to consider beyond those mentioned here.
If you do take the LSAT twice, expect different law schools to treat the two scores differently. Most schools will average the two scores, but some may use the higher score, some may use the later score, and some may ignore the second score unless it is significantly different from the first. You can find out how a particular school treats multiple tests by calling the school, but first, you should check the application catalog, which may provide the answer.