hii ali

for self preparation you must mainly good at basics i.e subject specially the mathematics , physics , chemistry.

please fallow the below steps for preparation

as of now you have 3 months in avereage in your hand for any exam first get good grip in the subject gain it

become perfect in formulas and start practicing the MCQs as per the sylubus while check where you stand after that fix where you are lacking

solve as varity of problem with diffrent toughness but dont go for more no of solveation since time is low

once you are done with these with all subjects then try solving old question paper , and solve as many as you can, these steps if you fallow its more than enough

regards