To get good grades in math, these steps are the key:
1. Practise, practise and practise, there is no use in just reading the chapters, try all the questions, solved examples. Look up online sample papers to do as well.
2. Time yourself, many people lose marks because they don't have enough time during the exam. While practising, time yourself and try to do it faster each time.
3. Memorise important formulas, it will be easier to solve questions. If you want to understand the formulas better, try to find their derivations as well.
4. Relax, and sleep this might have been said a million times, but its true, unless you sleep well the day before a test/exam, you will not be able to concentrate during the exam.
Hope this helped you get good grades, best of luck!