I am repeating my strategy here for your benefit. This strategy I have already put out in various Quora answers.
All these tips are based on the success I got in UPSC in 2014 Civil Services Exams and by no means is this an ideal or the only plan. Go step by step in all sections.
You should read The Hindu and The Indian Express daily and along with websites like Insights on India and IASBABA prepare current affairs.
For Ancient and Medieval History, I read just the NCERTs well. I focused on art and culture mainly here and made my notes keeping in mind UPSC Pre questions as this section is not asked in Mains.
For Modern History, I just read the Spectrum and revised it again and again.
For Art and Culture, I referred Nitin Singhania's notes available in the market and revised them again and again.
For World History, I read Old NCERTs and Norman Lowe. I made short summary of all the major themes in World History and revised these notes again and again. Try and link up World History and International Relations. It's easy and very useful.
For Post Independence section, I refered Vision IAS notes and made a short summary of their notes for my revision.
For Society part, I did nothing and just prepared Government Schemes from India Year Book, Economic Survey and newspapers.
For Geography section, I read 11th and 12th Class NCERTs and 10th class ICSE book. Here topics are straightforward and one needs to understand concepts. Try and remember some diagrams that can be made in the exam easily. Apart from this one must refer to Mrunal's videos on YouTube for Geography.
For Constitution and Polity part I read Laxmikant again and again. I especially remembered DPSPs so that I can use Constitution in most GS Answers.
For most other topics here like civil society etc one needs to use examples and data liberally from newspapers.
For International Relations section just read The Hindu and The Indian Express daily. Avoid World Focus and other books.
For Economics, go through Mrunal's videos on YouTube and his articles for the same on his website.
For major crops and their cropping patterns, I prepared the same from Geography section resources I gave above.
For rest of the issues such as PDS, subsidies etc I relied upon Vision IAS and GS Score material.
For Science and Technology I prepared the theory part for Pre from GK Today and current events for Mains from Insights on India.
For Environment it is better to refer to book on the same by Shankar IAS.
For Disaster Management issue I utilised 2nd ARC report and made a short summary.
For Internal Security one can read GS Score or Vision IAS material.
For ethics read the basic portion and prepare all the definitions of the concepts involved. You can refer GS SCORE here.
Regarding case studies you need no specialized knowledge to handle them. Remember these pointers:-1. Devote starting two lines to capture the actors involved and their ethical dilemmas.2. Next say that to solve this problem we can consider following alternatives and analyze the options given to you in the paper. 3. For each option now present the pro and corresponding con of it side by side so that it is easy to know the benefits and drawbacks of each option. 4. Present two two pros and cons for each option.5. Now come to the final part of giving a solution to the issue. Never select any option given in case study in totality.6. Start off by saying that there can be no single perfect solution. Then start with mildest solution. Say if this works it is fine, else give a more stronger solution. If this works it is fine or else give a more stronger solution and continue this way to give a set of continuous escalating solutions so that it feels that you are a real problem solver and that you just dont have a single solution. But in some cases you might not require such a solution as the problem might not be very complex as less number of actors might be involved. In such a case you should take a simple approach and take an ethical stand. It depends upon the case study the approach that you might require to follow. 7. At each point tell that your stand is backed by Constitution Articles, SC Judgements and in consonance with teachings of our founding fathers like Gandhiji or Nehru Ji or Ambedkar Ji.And hence I say you require no preparation for this part of ethics. Just use the above format and maximize your marks.
This is what all you need to refer. Now I will discuss my strategy for Pre which always gave me a 100% success in Pre. I completed all of the above sources well within time.Then having read that, I took up all Pre mock papers by various coaching institutes. Whatsoever Papers were available in the market I did them and made jottings of all those things that I did not know in those papers. Having done that I revised all my jottings.Now in the real Pre exam, after having followed such a strategy I used to attempt 90% of questions in GS Paper I as I had read so wide and prepared so wide. While I did not know exact answers to all, I still attempted them because you get very few sure shot questions in Pre. So you have to make educated guesses. This strategy will always ensure a 110+ marks in GS ie Paper I for you.While for Aptitude, my advise is just practice. Now it is just qualifying and you need not give too much input here.With the above strategy, you are guaranteed a 100% selection in Pre. Please don't start reading mindlessly all the NCERTs and all books you find mentioned here and there.
Next strategy relates to writing answers for Mains. To explain this I will take up an example. For eg the question is on corruption. More or less depending on question, you need to answer what is corruption, what are the causes of corruption, what are its positive and negative impacts and the measures to check it. Now look at how you can make this very easy. See the syllabus of UPSC and you find history, society, geography, politics, administration, economics, science and technology and ethics as major subjects. I use this approach to answer. Wield all these subject wise analysis into each and every question you need to answer about corruption. For eg look at the reasons of corruption. I think you can easily tell me historical, societal, political, administrative, economics, technology, ethical, judicial perspectives about why corruption occurs. From these angles you can also tell me the definitions and solutions. You can just reverse the reasons for the above points to gather solutions. If you know a relevant committee like 2nd ARC in this case it would help you give official look to your solutions. I hope this will enrich your answers, simplify what you need to remember and maximize your marks. This approach worked well for me.Remember this is a general approach. It might not work well everywhere. But in generality you can use this approach to
