I am sharing below my subject wise Prelims approach and some sample notes for your reference.

I. Ecology and Environment
1. A very important topic for Prelims — will continuously fetch many questions as IFoS exam is clubbed with CSE
2. Sources I had used:
– Shankar IAS Notes
– Vaishali Ma’am Notes (Vajiram)
– Vision Monthly and Daily Hindu for Current Affairs
– Insight IAS Prelims compilation
– Govt. Websites and Wikipedia of Major National Parks
3. Approach:
– Tried covering important topics from Shankar and Vajiram notes and supplemented them with current affairs
– For Reserves, National Park, etc. — tried remembering Biosphere Reserves, Ramsar Sites and Few Major National Parks through Maps — Remembered major Flora, Fauna and geographical features in the above. These can be used for option elimination during Prelims.
4. Also, went through websites of UNDP, UNEP, World Bank, etc. to cover the initiatives in India.
5. Test Series for Environment:
– Previous Year Qs in Shankar Notes
– Sectional Test of Vision and Vajiram
II. Modern History
1. Attracts a significant number of questions in Prelims every year. An important static portion which requires a good number of revisions
2. Sources I had used:
– NCERT (Bipan Chandra)
– Parmar Sir Notes (Vajiram)
– Vajiram Yellow Book for Modern History
– Crash Course Videos online
– Tables at the end of Spectrum
3. Approach:
– Tried getting an idea about the basic timeline after two initial readings of NCERT and watching a ~3hr long modern history crash course video online
– Supplemented information from the Vajiram yellow book into Parmar Sir Vajiram notes
– Created Governor/Viceroy wise event list (as shown in sample notes) to easily revise and remember them
– Used Spectrum tables as the source of factual information not yet covered
4. Test Series for Modern History
– Sectional Tests of Vision and Vajiram
– PYQs from last 5 yrs UPSC papers
5. Modern History has a lot of things to remember. Discussion of storyline and questions with friends helped me a lot in getting confidence in the subject.
III. Geography
1. Relatively lesser questions asked in the last few years but one must be ready for surprises
2. Sources I had used:
– NCERT XIth and XIIth
– Manocha Sir, Shivarpit Sir and Amit Sir Notes (Vajiram)
– Ratnajali Ma’am Videos (Mrunal) — Selective
– Pmfias.com to fill gaps
3. Approach:
– Covering syllabus through NCERT as well as notes
– Understanding concepts and discussion with friends for a better grasp
– Focus on Prelims specific Question areas: Rivers, Mountains, Vegetation, Biomes, etc.[Have added some notes above]
4. Map based Questions:
– Had a World Political, India Political and Physical Map in my room.
– Used to look at it during some break time again and again for memorizing
– Mark important visits and aspects like straits, choke points, SLOC, etc.
– Resources from Human Geography NCERT (used Geography Optional Map book for reference to fill gaps)
– Use of mnemonics provided by Amit Sir (Vajiram)
– Practiced StudyIQ Map based Question series
5. Test Series
– Sectional Tests of Vision and Vajiram
– PYQs from last 5 yrs UPSC papers
IV. Ancient and Medieval + Art & Culture
1. Low level of cost-benefit/input-output ratio. But as it is a competitive exam, selective and effective study is preferred.
2. Sources I had used:
– Tamil Nadu XI NCERT
– Jain Sir Notes (Vajiram)
– Fine Arts NCERT
– GK Today Notes (Selective for Literature, Music, Dance, etc.)
– ExamRobot for previous year questions
– Vajiram old yellow book (only some important pages)
3. Approach:
– Multiple revisions of TN NCERT, Fine Arts NCERT, and Jain Sir Notes to memorize
– Made different documents like Ancient History Timeline, Maps (uploaded above) to aid in memory
– Used to write difficult words in Devnagri Hindi for better retention
– Used PYQP to identify prominent topics — like Bhakti-Sufi, Jainism-Buddhism, etc.
– Analysis of options asked in PYQs for better coverage
– Used ExamRobot to identify other questions asked in those prominent topics in other UPSC exams.
4. Test Series:
– Sectional Tests of Vajiram and Vision
5. One of the most difficult portions for me as it required a lot of sequences, dates, names, etc. to be memorized. Took me multiple revisions but I still wasn’t confident till the end. But these revisions did help in the elimination of options in the final exam and I was able to do most of them correct.
6. As it is purely memory-based topic, discussion and storytelling of timeline with friends can help in better retention.
7. Also, watched YouTube videos for dances, referred to Images of artifacts and visited the National Museum in Delhi — were some of the efforts to aid my memory.
V. Polity and IR
1. Very important subject — attracts many crucial and interesting questions every year
2. Sources I had used:
– Laxmikant Latest Edition
– Ravindran Sir, Gautam Sir, Abhilash Sir, Abhey Sir, Iqbal Sir, Pavneet Sir Notes (Vajiram)
– Constitution Mobile App
– Bare Constitution Book
– Vision IAS Monthly for Polity and IR Current Affairs
– IAS Parliament for International Organisations
– Prslegislature website to fill gaps
3. Approach:
– Multiple readings of Laxmikant (almost whole of the book is notes, was futile to make notes out of it) and Class notes
– Had made notes for Constitutional and Non-Constitutional bodies (shared above) which were at the end of Laxmikant
– For Polity, Original Constitution and SC judgments were the go-to guides for any final interpretation
– For Prelims, FR, FD, DPSP, and basic terms were really important. Discussion and Analysis with friends used to help
– Current Affairs were also very important for both Polity and IR. Monthly magazines and compilations used to help a lot
4. Test Series:
– Sectional Tests of Vajiram and Vision
– PYQs from last 5 yrs UPSC Papers
5. Basic conceptual understanding is crucial for polity which develops from multiple readings. Questions in prelims majorly tries to confuse on that front. Post mock test analysis and discussion with friends aids to the understanding.
VI. Science & Technology
1. A limited number of questions asked but the topic is important as considered crucial with changing dynamics
2. Sources I had used:
– NCERT — only Applied Science chapters (generally at end of the book)
– Vinoy Sir, Rahul Sir and Bindu Mam Notes (Vajiram)
– Vision Monthly Magazine
– IAS Parliament Yearly Compilation
– Web surfing/Youtube videos for certain important topics
3. Approach:
– As the trend of UPSC is to ask mostly application based and non-technical questions, current affairs were the priority
– Focus on areas covered in Economic Survey, Budget, Nobel Prizes, Significant Discoveries, Defense Advancement, Famous scientists — anniversary and deaths (Dr. Stephen Hawking was asked)
– Avoided the core scientific concept which is required for Science exams
4. Test Series:
– Vajiram and Vision Sectional Tests
5. S&T portion tries to check general awareness and curiosity in this area. No need to get entangled in the complex scientific concepts. The aim should be to cover current events and related details which is expected of any curious individual.
VII. Economy
1. Important subject — many conceptual as well as general questions asked every year
2. Sources I had used:
– XII Macroeconomics NCERT
– Vibhas Sir, Samyak Sir and Kapuria Sir Notes (Vajiram)
– Mrunal Economy lectures
– Vision Monthly Magazine
– Budget Speech and other related documents
– Economic Survey Summary
– Investopedia to understand certain concepts
– Glance through NITI Aayog India @ 75 document
3. Approach:
– Watched Mrunal Economy lecture during leisure time as the test study (dipstick) during my job
– NCERT and Class notes helped in having clear concepts
– Avoided statistical jargons and technical economics. Focused on trends and basic concepts as per the demand of the exam.
– Discussion with friends helped in improving the understanding
4. Test Series:
– Vajiram and Vision Sectional Tests
– Previous Year Question Papers
5. Questions asked in Economy are from areas like BOP, Budget, Inflation, Financial Markets, etc. Clarity of these basic concepts is crucial for Prelims.
6. Global bodies like WTO, AIIB, World Bank, etc., their indices and India specific projects are important for Prelims
Sample Notes
I. Ecology and Environment
– Sample Notes
II. Modern History
– Sample Notes
III. Geography
– Rivers of India
– Vegetation of India
– Major Biomes of the world
IV. Ancient & Medieval + Art & Culture
– Maps — Art & Culture
– Classical Dances
– Other Sample Notes
V. Polity & IR
– Sample Notes
– Constitutional Bodies
– United Nations
VI. Science & Technology
– Sample Notes
VII. Economy
– Sample Notes
I have tried to cover all subjects from Prelims perspective with some sample notes. Hope they help you in some way.