Higher secondary students need to learn math's at totally a different level. Students at this level should be able to solve, non monotonous and open ended problems. The focus here should not be just the answer but the steps and formulas involved in going through the problems. As a student regulate yourself and learn to think on your own.
Do not set a target mark of 100/100. It's better to allow yourself to do mistakes and gradually reach to more percentages. This way, you are sure, not to repeat your mistakes. And every time you attempt a paper in math, you should only aim for another 10 more marks. This helps you to turn away from rote learning and go towards, self learning.
Real world math's is more important to develop competency in mathematics. In learning the formulas, it is also important to bank on your memory skills, as memory in the student age is very strong and gives you more confidence. Still your focus should be on creative learning at the higher secondary school level.
It is equally important to see that, math's learning in the class room is connected to real life situations. For example, geometry measurements should be related to big shapes and designs, like construction of houses, turbines, parks, dam's, bridges etc. A student should understand that if the sizes are not measured properly, it's not the answer which will go wrong, but crores of investment in the real world.
This way of learning all concepts in mathematics will make you more responsible and also give you direction to assess by yourself as to what you are good at in your career options in the future.
Also, it is just not enough to enter into a particular subject at the higher secondary level, without having a proper aptitude. So mathematics at this level is just not a competition and pride comparing with others, instead it should be a real passion which helps you to perform better.