if you are not from Science background then you must join any coching classes for that.
if you are from science background then you must be aware from all the topic of syllabus.
just practise more and more sum and always try to write formulas in every sum which will help you to remeber the formulas because if you think first you will learn all formula then you will go for sum. its good but there have chances to forget the formula but if you practise those formula while doing sum then you don't need to remeber them and never will forget them too.