Hello Vishal,

If you are currently studying in class 11th , then try to have a good concept on vectors, because it will be very helpful in class 12th physics. In the chapters like electrostatic, magnetostatics it will be very helpful in solving numericals of these chapters.
Apart from vectors, have a good concept on the waves, because it would be very helpful in optics chapter of class 12th physics.

Hope it will help you.