Hey varnita Singh , To prepare for any exam including BHU I would suggest you to start with the previous year papers. Collect the maximum you can , go through it , take a note and write down whatever you feel , like the content tested the most or the subject you find difficult and whatever factors you think is essential..now make a schedule and incorporate all the notes you made and stick to it. Read the concepts well and understand them..solve as many papers you can and time them .go back check your answers , analyse rectify the mistakes and solve again..the early bird catches it's worm , so start early and prepare smart. Good luck