My best resource while studying for the GRE Chem course was actually my class notes. I had purchased a Princeton Review book, but found that my studying was less efficient since the material was presented in a different way than I had originally learned the material. By studying from my pre-existing notes and text books, it felt more like a review as opposed to learning new material and I felt more confident going into the exam as a result. Your experience may vary depending on how useful your own class notes are to you. As you mentioned, it is wise to go over GRE practice tests as well. Best of luck.