GMAT Strategy

I took the exam for the first time back in September of 2010 and scored a 660 (42Q,39V) because I needed to get into graduate school for Spring 2011. I am retaking because I want a better score because I want to get into a PhD program. I am taking the test on January 17th and I have now until then to study for it. I was hoping you guys would be able to help me structure my plan. I bought the MGMAT books (I didn't use these for my first time around). I also have the OG 12th edition and the two supplementary books. I have some other materials, but I think those are the most important ones. Thanks