The first big question is whether you want to study on your own or with a class / tutor.

If you want to study on your own, take a look at Eric's blog and wiki (I'll let him add the links) - he's got a great outline of how to approach this.

If you want to take a course or work with a tutor, first identify any companies with which you might want to work. Then, attend any free sessions they offer to learn their approach and the abilities of the instructors. You're looking for clear, comprehensive materials and top-notch instructors (not just people who are good at taking the test themselves - people who are great at teaching others how to take the test). Any program you do use should DEFINITELY incorporate the official guide materials (these are the only real test questions from which to study). Then decide which program seems like the best fit for you.

Re: deciding between class and private tutor - tutoring is obviously more personalized, but it's also more expensive, so if money isn't unlimited (as is the case for most of us), then factor that in. Think about your own learning style - do you learn better in a group or one-on-one? How significant is the difference? For most people, I recommend taking a class just because, for most, private tutoring is too expensive. Really, I only recommend private tutoring if you have some special circumstance (very difficult schedule, learning disability, only want to work on certain things, have millions of dollars lying around, etc ).

Good luck!