Hey!

First clear your basic concepts of plane geometry and solve some basic questions from ncert, then try to solve the advanced level questions without looking at the solution. Once you are done with the practice of same, then solve the previous years problems.

For more information you can go through this link

https://www.google.com/amp/s/school.careers360.com/articles/how-to-prepare-for-kvpy/amp

Good Luck