hello 

bhaskar biswas 

The best preparation according to me first of all please study all concepts of NCERT books and later on please refer the reference books D C pandey is good but according to my suggestion please go through the H C Verma it is the best book to learn in the easy way .if myou already started refering the  D C pandey no problem but still yet no started refering book means please refer H C Verma

i hope the provided information will helpfull

good luck