Buy a GRE textbook.
The biggest mistake people make (even those math studs) is that they believe their good math skills will save them on the GRE. Its a different test entirely. Your old textbooks give you a problem and tell you what to do to solve it. GRE questions do not. They're meant to make you analyze what piece of information is given, and decide how best to solve it. Buy an actual GRE prep book (Kaplan is good). They are designed to teach you exactly how the GRE functions. In regards to the Verbal Reasoning-there's no trick to it. Build up your vocab any way you can. Good luck.
