Best tips to prepare for IAS exams is to read NCERT Books of Class 6th to Class 12th and work hard to crack the exam.
- For History – NCERT + Spectrums Modern India
- For Geography – NCERT + GoCheng leong + a good atlas like orient longman/oxford.
- Polity – NCERT + any good guide book like laxmikanth’s indian polity/ Jojo mathews’s Indian constitution and polity.
- Science – i think Ncert class 6th to class 12th is more than enough.
- Economy – NCERT class 11th and 12th + pratiyogita darpan’s special issue on indian economy + Read and make notes of newspaper about current economy.
- Mental Ability – R.s.Agarwal.
- Current Affairs – one has to be thorough with newspaper readings of atleast one year back from the date of exam.
- General Knowledge – India year book + Manorama year book or Chronicle year book.
Also check Tips to prepare for Engineering exams