Hey

 it is necessary to prepare well to get the good score in the examination. First of all, it is very important to know the complete syllabus from where the examination will be asked so you must go through the syllabus first . Time management plays a key role in achieving the good marks. Manage your time in such a way that every subject will get the equal attention. Provide more time to the subjects in which you are weak.Solve previous question paper of KVPY or practice mock test. It will provide you the idea about the examination pattern 

Now few of the good books for preparation are

• Prepare Ncert such that your concepts are on tips
• A Das Gupta by RD sharma in mathematics
• Fundamentalsof physics by david and halliday 
• Conceptof physics by DC Pandey
• Organic Chemistry by OP tandon