I have not yet started serious preparation for chemistry and physics for neet.I have 4 months left for neet.Please tell me how to do it

DEAR JULLEY 

nothing to worry about , 4 months are more than enough for you to prepare for that , 
just maintain your strength in biology , as thats the imp subject and 50 percent of the ques comes from that chap . 
and in chemistry , just focus on the imp chapter , 

frst start with structure of atom and chemical bonding , please dnt ignore that two chap , then go with organic completely . 
while in physics start with kinematics , then rotational motion , then 12^th magnetism part , u can do this much easily in 4 mnths . 
also , alongwith that do the prev year questions , they are very very imp 
HOPE IT HELPS 
REGARDS 
UMAKANT