Although, the introduction of environment, ecology, climate change, biodiversity and sustainable development seems to suggest that these are new areas, the questions related to these topics have been asked in the past. This merely suggests that these areas may carry more weightage than they used to do in the previous years. Thus, one needs to have a slightly tweaked approach towards the preparation for the GS paper.
When one starts preparing for GS Prelims, one may feel that anything and everything under the sun is asked. The student gets confused about what to study, which things to focus on, which reference material to use etc. To be honest, GS is an ocean (in fact a vast ocean) and there cannot be a totally comprehensive list of preparation material. Having said that, if there is a focused approach to the preparation, one can find a method in this madness.
What to prepare for GS Prelims:
History of India and Indian National Movement :
Although, the title is history of India, the major focus of the GS history section has always been "Modern India" and the "Indian Independence Struggle". As this is an important area for the mains as well, a proper study of this area is recommended. A thorough study of NCERT books of class 8, 9 and 10 should be a starter.
Indian Polity and Governance:
This section carries a lot of weigtage in the GS section. The section covers constitution, political system, panchayati raj, public policy, rights issues etc. A thorough study of the constitution is required, one must go through Our Constitution and Our Parliament. The articles on the powers of President/ Governors, Fundamental rights, election procedures are important.Newspapers articles related to government policies, special measures like NREGA etc. should be prepared. Keeping newspaper cuttings or making notes from daily newpapers is recommended.
Generally, conceptual questions are asked and one also needs to know important articles and amendments. For instance Article-143 is concerned with President of India seeking the Supreme Court's opinion on any important issue and 73rd Amendment Act is concerned with Panchayati Raj Institutions.
The GS prelims general science has focus on biology and some questions from Physics and Chemistry as well as Indian Space research. Do refer to the work or terms related to recent Nobel prizes in these subjects. The Hindu Science and technology supplement is a good source. Look at the past few years' papers for an idea of what kind of questions can be asked. In cases, where you have confusion and need more detailed information or clarity of the idea, use wikipedia.
Economic and Social Development
The economy part of the section can be covered by focusing on budget, economic survey, social sector spending, new schemes, their budget allocation, points covered etc. Terms related to WTO, stockmarkets, foreign investment, etc should be studied. For the social development part, newspaper reading should be sufficient, specially running up to the budget and for a few days after it. Understanding which scheme means what is important. The syllabus specifically mentions inclusion, poverty, demographics, social sector initiatives etc, hence it is very important. The Hindu Economic survey is a good source too.
India and World Geography
Mostly Atlas/ location based questions are asked. Hence, while reading newspapers, keep your atlas handy. A good idea of India and world map will stand you in good stead. Location of countries, important rivers, which countries are cut by tropic of cancer/ capricorn and equator etc. should be studied on a regular basis from an Atlas.
Read 'India and its states' portion from India year Book.
Note down all important national parks and their locations (which state) as it is asked often in match-the-column type questions. Sometimes questions related to rainfall and vegetation are also asked. Refer to Census data as well. India year book can be downloaded from Government of India’s website.
UPSC specifically mentions Current affairs of national and international importance. Hence, this should be kept in mind while preparing for current affairs, thorough reading of the front page, editorial, op-ed, national, world, economy and sports is very important. If you are short on time and cannot read two newspapers, read either Hindu / Times of India and supplement it with one magazine. The choice is yours, either Civil Services Chronicle, Civil Services Times or Competition Wizard. It will help to stick to one of these. These magazines are very helpful for current affairs and save a lot of time. Focus on major awards, new initiatives, global summits, books, India and neighbors, India and world etc.
A reading from any year book is also important. Keep your atlas handy while reading the newspapers. Also important is to take notes or to keep the cuttings of important articles.
The Hindu also publishes a diary of events on the 8th of January every year. That can be used as a good source. Mark all events of national and international importance in it.
It's a good idea to make notes while reading newspapers and studying books and other reference material. This helps when you are revising for the exam. While making notes, make sure that you do not copy everything, otherwise the whole purpose gets defeated. The notes should be short, to the point and capture important information. They should serve as a tool to memorize lots of information.
Do not read more than one magazine. Most of the magazines carry similar (if not same) information, and thus you will end up wasting time. Select any one and stick to it. While reading the magazines, make sure you are reading the portions relevant to UPSC GS only and not for other exams.
The exam is about scoring and qualifying, so if you have trouble in some areas, it's fine- you do not need to know everything. The major focus should be on consolidating what you know well.
Look at the past papers at least once or twice to get a general idea of what comes and how to extract information from various sources. It is very important to have the test paper at the back of your mind throughout your preparation.