Use / to steer, hold to crouch and go faster. Push / to push. The bigger the rider, the harder they push.
Hold down to get ready to jump, release to jump.
The bar at the side of the screen is your boost bar, press to boost. Do tricks to give you boost.
When in the air press the shoulder buttons to do grab tricks. While doing a grab trick press to tweak it.
There are 15 combinations of grab tricks you can do, not including tweaks. Each character has different grab tricks.
To spin: when holding down hold down the direction you want to spin, then release before you reach the top of the ramp but hold down the direction, and you will spin.
To flip do the same as spinning but hold /.
To grind, just land on a rail, turn sideways to balance easier by pressing /, or keep on pressing that do do rail spins.