for studying math and science effectivly u need to make atime table for that .
as u knows better urself then do find out your strong and weak area first ..
do take breaks at regular interval as it will refresh your mind,,
change the subject at regular interval, it will help u to retain more..
donot mug up anything, try to understand the concept first , it will help u to remember anything more period of time..
Math, being an abstract subject demand s a lot of practice , so do practice as much ques as u want for maths..
HOPE IT HELPS