I've found a easy strategy in farming 10.000.000+ points in School 2.
1) Go to School 2's "secret area".
2) Go to the grind + wallride spot (watch the video).
3) Hold the grind button the entire time and spam the jump button while in the grind area.
4) Wallplant in the walls
5) Do some grab strunts to earn more points
This strategy surely can be optimized, so be free to try more things to farm more points.