First chalk out the Syllabus of KVPY SA or SX whichever youre Targetting and start referring to your JEE/NEET Preparation Material for the relevant chapters. Once youre done with the Syllabus you may seriously Solve the Previous Years Papers of KVPY, Analyze the Questions and Solutions and make notes. Try revising these before the exam besides finalizing on a Exam Preparation strategy. You may even consider Test series for KVPY from some of the Edtech Platforms like Toppr etc.

For more information about KVPY Preparation do follow the link below

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