How hard is it to get an A* at A2

Last year I achieved 3 A grades in my AS. However, this year I would like to achieve A*'s in both Religious Studies or Geography. What should I do differently this year to achieve this. What separates an A* student from an A student.

Btw I achieved 84% UMS in Geography, and 92% UMS in RS

Last year I achieved 3 A grades in my AS. However, this year I would like to achieve A*'s in both Religious Studies or Geography. What should I do differently this year to achieve this. What separates an A* student from an A student.

Btw I achieved 84% UMS in Geography, and 92% UMS in RS

The main thing that separates the 2 isn't so much knowledge but tackling exam structure (unless its something like maths in which case, the difference is knowledge). In exams like RS and geography you're limited with time, pouring out the knowledge will get you an A but looking at mark schemes and examiners reports to understand what they want and giving them that, is what will help you get the A*