The big thing that was holding me back from getting this achievement was that I was pressing the left stick in different directions to do different tricks. You don't have to do that. That will only slow you down. Whenever you go off a ramp or whatever, just press the left stick in one direction repeatedly and then, just before landing, mash LB and RB to do a "finishing trick". The specific level I got this achievement on was the rival battle against Shadow. Good luck!