Luckily, I've always been a very good standardized-test taker. That helped. But I did a lot of prep too.
I bought a book of actual former LSAT exams. I took a first test with no prep just to get a baseline (164). Then I worked through a large number of logic games questions because they are of course the trickiest part. After that I took several more practice tests in the week leading up to the exam (172-176). About a week and a half before the real exam, I realized that I was getting bored with the repetitive test taking and wasn't focusing all my attention on it the way I should be, so I just stopped. I took one final practice exam, then scored 175 on the real test.
I would suggest, if you are already a good test-taker, don't waste your time with the "strategies and explanations" type of test-prep book put out by Kaplan, Barrons, or any of the rest. It's exactly the same advice you would get for the SAT or GRE - read all the answer choices, eliminate definite wrong answers, etc. The books of real tests, answers, and nothing else are much more helpful. The big exception to this is if you're having serious trouble with the logic games section, since there are actual strategies you can learn to do better on the games.
Also, just because you have a book of full-length tests doesn't mean you have to take a whole test all at once. If you're having trouble with games, do just the games sections. When you run out of time, finish the rest of the problems anyway.