Hello Simran Mathur,

I am glad helping you with this ,but here are some tips which would be helpful for the preparation of NDA exam . 

First of all ,you should be clear with your basics and as if your basics are clear then you could go with higher level of questions .Secondly ,proper selection of materials ,sample papers and books is must .You need plan a well organized schedule for the preparation of your exam .And moreover ,the selection of NDA aspirants is not only on the basis of written test ,but also physical and mental wellness ,healthy aspirants are taken .So be safe and stay well and healthy with proper diet and sleep .Finally ,good luck .