It is very important to solve the previous year papers. Download the papers. The previous year papers can be found from the IIT website. The link: Welcome to GATE-JAM Office IIT Bombay For inorganic, Take J.D. Lee book and start reading it. After that solve previous year question from each chapter. For physical Chemistry buy Puri, Sharma and Pathania. Read the chapters like 1) Thermodynamics 2) Chemical kinetics 3.) electrochemistry 4.) Chemical Equilibria and Ionic Equilibria 5.) states of matter 6.) colligative properties 7.) quantum chemistry and solve questions from them. Buy Arihant chapter wise chemistry for JEE. A good book for solving problems. You can Also buy any book having previous year papers of JAM chemistry. For Organic, you can study from Jagdamba Singh, L.D.S. Yadav or any standard text book. Doing JEE level basic organic from class XII books will also help you a lot.