Get one of the study guides - you can pick these up in bookstores or on Amazon. I think Princeton and Kaplan both have ones with CD rom's so you can "take" sample tests in the same format that the test is given.
The math portion will be pretty well covered in the book, as will the verbal. The trick is the analytic section. Here is how they separate the "wheat from the chaff" as it were in the analytic test. There are three kinds of questions: ones that you can solve mechanically (so it makes sense to do little charts etc), ones that you can't solve, but can easily eliminate the wrong answers, and (this is the tricky bit) ones where if you shift your perspective from the details (which got you the first two kinds of answers) to the whole - it's easy to see what the answer has to be. Generally the are given in that order - so the first question in a set will have a mechanical solution, the second a negative solution, the third a wholistic solution. If this doesn't make sense, I'll write more. This kind of "perspective switching" is what the sort of people who become philosophers "do" naturally - so if it doesn't come naturally to you, you are a normal person!:) But I can explain it more to help you "get" it.
