To be eligible for UPSC, you should be atleast 21 years as on August 1st of the year of you appearing for the exam. For example, if you were born in 2000, you should be 21 years atleast by August 1st, 2021. If you will turn 21 by August 1st, 2021, you can appear for UPSC in 2021. Or else, you can appear for the exam only in 2022.

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.

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.

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.

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.