Start with the NCERT foundation, then choose books you can understand and read again. The guidance below comes from the full preparation guide.
How to choose books you can study and revise
After NCERTs, you will need more detailed material for the syllabus. This is often when the search for a perfect book begins. You see an old UPSC question about a detail of Buddhism or Jainism, but cannot find that detail in your book. You wonder whether the book is good enough and start looking for another one.
You do not have to throw the book away just because it did not contain that one answer. No single book can cover every fact UPSC might ask. A very unusual question can leave even well-prepared candidates guessing, and a correct answer may simply come from luck. So do not worry about your book missing one such question or let it make you doubt your whole preparation.
Choose books you can finish and revise
Look at how well the book covers the syllabus, explains the concepts and helps you answer questions across the subject. If an important topic is missing or poorly explained, use another source for that topic. But one rare question is not a reason to replace the whole book or keep searching for a perfect one.
Keep your sources limited. It is better to read one good book five times than to read five different books once each. Reading the same book again helps you understand the concepts better and remember more. When you practise questions, you will see which parts need another reading. But if you keep adding new books, you will have less time to revise what you have already studied.
The earlier NCERT work helps here too. When a basic concept is familiar, you can connect new information to it. You are adding to something you understand. That is another reason to do the schoolbook reading carefully.
Read a sample chapter before choosing a book. Even a widely recommended book may assume knowledge you do not yet have. If you cannot follow it, use a simpler source to understand the basics before returning to the larger book.
The UPSC booklist offers choices. The value comes from studying and revising suitable material, rather than buying everything on the list.
Get the NCERT textbooks
Use the official NCERT e-book page to find the textbooks. Read how to work through an NCERT chapter before moving to detailed books.
How should I revise a UPSC book?
Read the same suitable book again to understand the concepts better and remember more. Keep your sources limited so you have time for this revision. Practise questions and read the explanations to see which parts need another reading. If you keep confusing a point, a short note can help; keep it brief.
For current affairs, follow the newspaper-to-prepared-material approach. For an optional, read how to choose a subject you can prepare well.