I took it, and L.C. and AJ can probably give some good advice.
My only advice is to take the practice exams as many times as possible under timed conditions. Many of the people I know were not comfortable with the time given per section and either try to blast through thinking they don't have time to finish, resulting in missed questions they would have otherwise gotten correct. Or they take too much time in the beginning and end up rushing at the end of each section just wildly filling in answers that they didn't leave themselves time to read the questions for. Obviously work on the section(s) you perceive to be your weakest, whether it's reading comp, or the logic or whichever, the key really is, like everything else, to be prepared to the point where your nerves are not going to interfere with your decision making. Sounds obvious, and it is but it can be nerve racking. Short of Ritalin or Aderol, Adderal or however you want to spell it, being prepared is the best remedy for the assault on your brain that you will endure. If you can keep your nerves quieted and get comfortable answering in decent time, I'm sure you'll do fine. (It's hard not to be nervous considering how much weight is put on your score in terms of acceptance) Being set on where you would like to go to Law School (and you will apply to them, so you will be at some point) and what their median scores are, combined with any previous scores if you've pre-tested will give you a good idea of where you stand and can ease or heighten the pressure tremendously. Since you are taking it this Fall you will have a time to retake it before you go anywhere, if anything goes wrong, and I believe now schools use your best score and not all of them. If you have a pre-test score to go off of already and know what your GPA will be, or likely be, you can find the range schools here: http://www.studentdoc.com/law-schools.php
Good Luck! And remember, at least it's not the MCAT.
Also, if you run out of the P.E's in the books, I think that The Princeton Review Online has P.E's you can take on their site. You likely have to sign up, so they can send all of their great deals to you. That being another option if you have the coin; taking a prep course, Kaplan or Princeton Review...but they can be 'spensive.