Learn about the test and all of the prep material by studying a simple prep book (Princeton Review should be fine) and reading all the material on these boards. Inventory all good CATs that are available. When you have all of this, build a study schedule that you can work with. Emulate other people who have written successful stories.
Notice: At this point, you really haven't done any actual prep work.
When you're working through the lessons and problems, spend some time on the math and verbal forums. Ask questions, take risks, answer some questions (with explanations). You want to get those mistakes out of the way during your prep, not during your test.
Good luck.