Get some air, then hold the Trick button and press the indicated button(s) to do the corresponding move:

Bar Hop: Press Triangle(2).
Can Can: Press Square(2).
Cat Nac: Press X, Circle(2).
Catwalk: Press Square, Triangle.
Cliff Hanger: Press Circle, Triangle.
Coffin: Press Triangle, Circle.
Cordova: Press Circle, Triangle(2).
Disco Can: Press Square(3).
Heart Attack: Press X, Triangle.
Heart Breaker: Hold Analog-stick Down until you have done a complete flip.
Heel Clicker: Press Triangle.
Helicopter: Press X, Triangle(2).
Indian Air: Press X.
Kiss Of Death: Press Circle(2).
La-Z-Boy: Press Circle, X.
McMetz: Press Triangle(3).
Mulisha Air: Press X, Square.
Nac Nac: Press Square.
No Hander: Press Circle.
Nothing: Press Circle, Square .
Pendulum: Press Square, Circle.
Rocket Air: Press X, Circle.
Rodeo Air: Press Triangle, X.
Saran Wrap: Press Triangle, Square.
Seat Grab: Press X(2).
Suicide Flip: Hold Analog-stick Up until you have done a complete flip.
Superman Indian: Press X(3).
Switchblade: Press Square, X.