Geography - Read NCERT books from Classes VI to XII. Also go through Physical Geography by Goh Cheng Leong. While reading geography refer to Atlas and supplement it with map work. This helps in remembering the topic better. Also read extensively on the climate types, soil types, rivers, mountains and geographical features of India. Try to understand how these have impacted India in varied ways.
Environment and Ecology: The best way to prepare for this section is net based research. Before you begin with the same, read the environment portion in India 2012 book. Try understanding the basic concepts like biogeographic zones, difference between wildlife sanctuaries and national parks, biodiversity hotspots, RAMSAR Convention etc. Also go through the chronology of environmental conferences starting from Stockholm Conference in 1972 to UNFCCC Durban Summit of 2011. Read carefully the policy decisions taken. Also ruminate on India's standing at these multi-lateral forums. Go through the basic concepts of global warming, carbon trading, carbon sequestration etc. Also read on sources of energy esp. on new non-conventional forms. For eg: Coal bed methane, Shale gas reserves. Read on fossil fuels and their impact on climate. Also read on major policy initiatives taken by India to address environmental concerns. All these topics and similar ones have to be read on internet.
Polity: Read DD Basu's Shorter Constitution of India. Supplement it with PM Bakshi's book on constitutional provisions. Try to grasp the intent behind a particular body/organization. Read in detail about the new constitutional amendments (from internet and newspapers). Check on basic concepts like secularism, DPSP, seperation of powers, Union, state and concurrent lists and the like.
Economy: Read Uma Kapila's Performance and Policies. Also read NCERT books for Classes XI-XII. While reading the newspapers, make a note of the economic terms you don't understand and research on them. Try to understand the concepts rather than mugging up. Also go though the economic survey and 12th five year plan and Annual budget. Economics is like maths and is fun. :)
Science and Technology: For basic science read NCERT books from Classes VI-X. If you have extra time you can go through physics for higher secondary and human boday and plant kingdom portions from higher secondary biology. For technological developments, read The Hindu's page on this topic every Thursday. Also read about the new innovations and developments in field of medicine like stem cell research, 3V Avataar, Pentavalent Vaccine, Japanese Encephalitis etc. Again check and research on all the technical terms you come across while reading newspapers. Also go through the nobel prizes in different strems. Don't just mug up who has won the prize and for what. Go in more detail. Like if Nobel Prize for Chemistry is awarded for research on quasi crystals, read on what quasi crystals are, what is their importance and what have been the new breakthroughs. Also read the Union budget plan when it comes out and read on new technologies government plans to introduce.
Current affairs: Read a good national daily like The Hindu or Indian Express on a daily note. Flag the articles and make notes. Revise them on a consistent basis. Half of the preparations can be done if one carefully reads and covers all relevant topics in a newspaper. Also read one exam oriented magazine like Wizard, Chronicle or PD. Reading Frontline is important but relevant articles should be identified. Just remember that the idea is not to gobble up any information you come across but assess the information from an exam oriented view and then focus on the same. For topics that are fleetingly mentioned in newspapers, rely again on web.
I hope that this was of help. Wish you all best.
