I've never taken the LSAT and I never will, but I pwn standardized tests for the most part.
Assuming there's a multiple-choice part:
If you answer a question then go to change your answer, don't. 70% of the time your first answer was correct and you'll be changing it to a wrong one.
Get lots of rest in the days before, eat a nice big breakfast, and have a water bottle handy if you're allowed in case you get thirsty. Dress comfortably in layers so you can put on or remove various articles of clothing as needed.
If the test is given by the same people that give the SATs, you can demand things and they have to comply--like if you want a left-handed desk, or the ticking clock is bothing you and you need to switch rooms, stuff like that. That's what I heard, anyway.
Best of luck!