Hello,

In order to become IAS, you have to appear for UPSC Civil Service Exam for which the eligibility criteria is passed graduation in any discipline from a recognized university, you need to attain 21 years age, the exam is conducted in three stages namely prelims, mains and personality test.

Preliminary : First Stage is MCQs based exam, it has two papers and each one consists of 200 marks,its numbers ain't added to final list, you just need to score the required cut offs against your category.

First is GS Paper-I which consists of the following topic such as History of India and Indian national movement, Indian and World geography, Economic and social development- sustainable development, poverty,inclusion demographics, social sector initiatives etc,Indian polity and governance-constitution,political system,Current Events nationally and Internationally, General Science,General Issues on environmental ecology,biodiversity and climate change. you just need to score the required cut offs against your category.

Second Paper is CSAT which is qualifying by nature,you need to score merely 33% which is 66 marks out of 200, it includes following topics such as basic numeracy, comprehension, logical reasoning and analytical ability, general mental ability, decision making and problem solving, interpersonal skills including communication skills.

Mains : This is a second stage which it's more of a subjective type, you are required to write answers for Four General Studies Paper such as

GS-I includes Indian Heritage and Culture,History and Geography of the World and Society,
GS-II includes Governance, Constitution, Polity, Social Justice and International Relations,
GS-III includes Technology, Economic Development, Bio-Diversity, Environment, Security and Disaster Management,
GS-IV includes Ethics, Integrity, and Aptitude
Two Optionals,
One Essay,
Two Language Paper

In total there are nine papers in Mains, and each paper is of 250 marks, total adds up to 1750 marks.

Interview : The two stages are further followed by personality test of 275 marks. This tests a broader aspect of your personality, it covers various topics related to your background, academics,home state, college, work experiences(if any) and various such relevant details, this is not a knowledge based judgement process as your knowledge are tested in the earlier two phases, but one thing you must continue doing is reading newspaper, many current events questions will be asked and remember to have a well-balanced opinion.

In order to start your preparation, go through the following steps;

Be well acquainted with UPSC Syllabus ,  this will help you to know what to read and what to skip.

Have an integrated approach, don't prepare separately for Mains and Prelims.

Make a timetable,set targets on a daily,weekly and monthly basis to cover this extensive syllabus.

Newspaper reading is important for preparation, you can start with any newspaper like The Hindu, or Indian Express.Put a more emphasis on editorial part, it will not only broaden your perspective but help a lot in answer writing, You can also make notes of this,it'll be very useful in answer writing.

When it comes to reading books ,start with basics for each subject, you can do with NCERTs for this. This will build your foundation strong,as you progress, move on to other relevant books as

History ; NCERT Class XI and XII /India's Struggle for Independence by Bipin Chandra/ art and culture by Nitin Singhania

Geography ; NCERT Class VI to XII /GC Leong's Physical Geography
/World Atlas

Economics ; NCERT Class XI /Indian Economy by Ramesh Singh

International Relations & Polity ; NCERT XII Political Science with current affairs /Indian Polity by Laxmikanth

CSAT ; Verbal and Non-Verbal Reasoning by RS Agarwal /M Tyra's Quicker Maths


Coming to Mains Exam, you can refer the following books for four General Studies Paper;


GS I - For History , Class XI NCERT book with India's struggle for Independence by Bipin Chandra,India after Independence by Bipan Chandra,History of Medieval India by Satish Chandra. For Geography refer World Geography and Geography of India by Majid Hussain, GC Leong's Physical and Human Geography with NCERT Class XI book.
For GS II - Polity and International Relations , refer Indian Polity by Lamikanth,India's Foreign Policy by Rajiv Sikri
For GS III - For Economics refer Indian Economy by Ramesh Singh, read ARC report along with Economic Survey and Fiscal Budget.
For GS IV - For Ethics refer a book named Lexicon by Niraj Kumar, also you can go through study material of IGNOU.

Keep resources minimal, read one book many a times instead of many a book one time,  revision is the  key here.

Writing mains is a huge task, for nine paper it requires immense practice along with knowledge. So, you have to start practicing answer writing in advance, even in a little way, There are many sites which provide questions on daily basis you can avail that. Try to give a holistic viewpoint while answer writing by providing political,economical and social aspect. You can get topper's answer sheet from various sites, try to analyze and study them minutely, you'll get an ideas about what to write, how to express and present viewpoint in organized manner.

Practice previous year question paper which you can get from the official website of UPSC.

Apply mock papers, and test series on a regular basis to evaluate your preparation level.