IAS exam preparation is not about studying 4-5 syllabus books. The whole IAS exam preparation that is divided in three parts: Prelims, Mains and Personal Interviews need thorough study. Besides reading the syllabus books, you also need to stay updated with the happenings around you. IAS exam preparation includes NCERT books, subject books, GS books and optional subject books.
If you ask online, everyone will suggest you different book as per their convenience. Following every suggestion might confuse you and can affect your preparation. So the right idea to study for IAS is to take help of experts at reputed coaching centers like Vajiram and Ravi. The teachers at the IAS coaching institute guide you at every step like book reading techniques, note making techniques, time management, mock exams and GD.
Initially, you might start with self-study, but to gain more insights about the exam and the right preparation strategies, you must join some coaching center.