1) Set Your Routine
In order to perform your best mentally you need to perform your best physically. This means you have to condition your body to be at its peak performance on test day during the test time. Seven days prior to the test begin to practice your test day routine. Wake up, eat breakfast, have your coffee and go off and be active the entire morning. Setting your routine during the hours you will be taking the LSAT will help you perform your best because your body will know when it needs to be at work. You don't want to suprise your body on test day by waking up early and dumping coffee in it. Nobody likes bad suprises.
2) Practice Trouble Areas
Everyone has one test subject area that gives them trouble. Use the last week before the LSAT to study your trouble area. If you try to marathon study by doing full practice tests at this point you will overwhelm yourself. Take a deep breath, calm down, and make your studying count - quality over quantity.
3) Prepare Your Test Materials
Gather you admissions ticket, pencils, erasers, ID, and any other materials and put them in a clear plastic bag on the Thursday before the test. You will thank yourself on Friday night and especially on Saturday morning for being prepared because you do not need any additional stress on the night before and day of the LSAT.
4) Take it Easy
On the night before the LSAT you need to let your mind relax. Do not do any practice questions. Instead, take a run, watch your favorite tv show, and be confident that your preparation is going to allow you to do your best on test day. As scary as it may sound, there is nothing you can do on the night before the LSAT that is going to prepare more than the studying that you have done for the last few months. Be confident in yourself and go kick butt on the LSAT!