Hi

To start your preparation  first of all go well through syllabus  , you can check the complete syllabus at
https://competition.careers360.com/articles/upsc-ias-syllabus

Top books which you can follow for UPSC examination preparation are listed below subject wise:-

HISTORY

*NCERT XI (Ancient & Medieval)
*NCERT XII (Modern Indian History)
*Facets of Indian Culture Spectrum
*From Plassey to Partition - A History of Modern India

Indian Art & Culture

*Indian Art & Culture - Nitin Singhania

Polity

*NCERT IX-XII
*Indian Polity M Laxmikanth

Geography

*NCERT VI X (Old Syllabus)
*NCERT XI, XII (New Syllabus)
*Certificate Physical Geography G C Leong
World Atlas

Economics

NCERT XI
*The Indian Economy Sanjiv Verma
*Indian Economy by Ramesh Singh
*Economic Development & Policies in India Jain & Ohri

Environment

*Class XII Biology (last 5 chapters)
*Environment by Shankar IAS Academy

International Relations

*NCERT XII (Contemporary World Politics)
*Current Affairs ( read newspaper )

To get the complete list of books go through
https://competition.careers360.com/articles/books-for-upsc-ias

*Make a routine or a time table , keep short breaks of 20 to 30 minutes after every 2.5 to 3 hours

*Read newspaper daily and keep yourself updated with the current affairs

*Choose your optional subject wisely , choose the subject you have interest in.

*Make short notes after completing each chapter

*Revise :- there's no point of preparing for the exam if you couldn't recall anything in the UPSC Examination so you should stress on revision as well.

*Solve previous year question papers and mock test papers ;- You should solve these , it will give you idea of types of questions asked and their difficulty level and will help you a lot.

*Also work on your communication skills and personality development as it plays an important role in your interview round

For more tips go through

https://competition.careers360.com/articles/how-prepare-for-upsc-ias

Thankyou