The LSAC, the makers of the LSAT, have provided a lot of good, free LSAT practice materials. But they're buried amidst a lot of dull administrative information, so I made a list of what you should read.
First, the LSAC provides general information about the LSAC. The best part about that page is the 19-minute video “About the LSAC”. I highly recommend it. It’s a great overview of the test, and it covers things that even many experienced students are unaware of.
Free Sample LSAT Explanations And Practice LSAT
Next, the LSAC provides sample questions for every section, along with explanations. These are a great orientation to the test, and it’s one of the few places where the LSAC provides *official* explanations for LSAT questions.
Lastly, the LSAC provides a full LSAT, for free. You can download and print the June 2007 LSAT. This was the first LSAT that used comparative reading. It’s a recent LSAT, and you should definitely take it before test day.
That’s about it. The sample questions I linked to can all be found on the LSAC’s prep materials page. Ignore the html versions of the sample questions and June 2007 test - they don't follow the regular format for LSAT questions.
There’s one more page you should read in full: Day Of The Test
It’s long, and a bit dull, but it’s extremely important. It tells you exactly what to bring and what not to bring on test day. Some highlights: No cellphones in the test center(!), only use wooden pencils, no rulers, no digital watches. Read the whole thing.