it really depends on the trick though, what part are you trying to draw your audience's attention to? you need to keep this in mind. do you want the audience to focus on how big the rail is? how large the drop is? the technical trick the skier is trying to do. what is your focus?
with this in mind here are a few of my favorite angles
if its a press or something get REALLY close and make sure the press is obvious in the composition of the shot
270 into something skinny? nosebutter in? maybe start on the lip of the rail and ski backwards with the camera REALLY (almost touching) close to the rail (need a stabilizer or something so that the rail itself doesn't distract from the skier - gotta be smooth and the rail seems to "flow" past. make sure the rail is taking up a reasonable portion of the frame)
single trick (not a line) - consider pulling focus from something in the background to infinity then pan with the skier as they ride the rail
* could just have something cool in the background and pan to skier cityscape, sunset, etc as the skier gets closer - consider pulling focus at the end to make the shot not in focus and perhaps pan up or into a tree etc (makes editing transition easier)
single trick onto a street entry rail - start on the side of the skier and ski across the lip, facing the bottom of the rail the whole time (kind of like a really large slider but only across the "lip pad" just in front of the rail at rail height)
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Just plan your shot so its not always the same thing over and over. even if the skiing is awesome it gets boring. just vary the camera angles so that you don't have the same ones back to back when you edit and it instantly makes it more entertaining