UPSC is a 3 stage selection process involving Prelims, Mains and Interview which tests your personality test. Prelims has 2 Papers namely General Studies and CSAT.
Every year, lakhs of people apply for UPSC exam while more than 90% of them fail to qualify. So it is a myth that the exam is easy. We can help you with few things that you need to consider before you start preparing for UPSC.
CSAT has Comprehension, Interpersonal skills including communication skills, Logical Reasoning and Analytical ability, Decision making and problem solving, General Mental Ability, Basic numeracy and Data Interpretation.
General Studies has Current Events, History of India and Indian National Movement, Indian and World Geography, Indian Polity and Governance, Economic and Social Development, Environmental Ecology, Biodiversity and Climate Change and General Science.
Because the syllabus is wide and not is confined to a particular subject, it is a myth when someone says that the syllabus is easy. The syllabus is endless and the Prelims is just a tip of the iceberg.
You will need atleast to start preparing ahead of 1- 2 years. If you are preparing at home, you need to keep yourself away from distractions and focus on the goal ahead. Gather as much as information as you can on each topic and keep yourself updated. Practise mock test papers.
Always select an optional subject whose material is easily accessible, you are interested to read it and also gives you an alternative career path. Do not play "Eeny Meeny Miny Moe" while picking an Optional subject. You have to pick a subject that interests you not by statistics of previous years toppers and their optional subjects.
Always remember to get the basics straight first. Most books only go for Advanced knowledge. But if your basics aren't clear no point in going for such books. So first prepare from NCERT and then for additional books. Your approach over a question is checked in Mains and so it is important to have a clear conceptual understanding.