You can do your preparation in either English or Hindi Medium. See UPSC has the upper age limit till 32 years. So if you can't start your preparation now, then also you have quite a good time.

Now if you are really passionate about the UPSC, then you can choose subjects as History, Geography, Economics, Political Science etc as your graduation subject. This will help you to gain basic to advanced knowledge about the subject and as this subjects are in the GS paper of the the UPSC CSE, then you will get some background about it. So you can choose this.

Apart from this you can make yourself accustomed to reading newspapers such as Hindu and keep a routine of study. The habit of persistence is the most important thing for a student who want to appear for UPSC CSE.

To know more about the preparation tips of UPSC CSE without coaching, visit the link below:

https://competition.careers360.com/articles/how-prepare-for-upsc-ias-without-coaching

To know more about UPSC CSE 2022, visit the link below:

https://competition.careers360.com/exams/upsc-civil-services-exam

I hope this answer helps. All the very best for your future endeavors!