Simple to just crack it you need to study NCERT well for chemistry and solve questions from any book but do solve all the problems from the same book because if you switch the books then you always will solve easy problems of every new book you take and leave it after you get bored please don't do they try to extract as much as you can from the same book you choose this will improve your efficiency and productivity for maths you need to be clear with basics properly and remember all properties and theorems well and practice problems of the same you can any standard book for chemistry maths and physics available and same for physics also.most importantly discipline is the key which will fetch you marks because if you be disciplned and study everyday then you will come out with glyfly colours..Best of Luck...