In general, what I've also found, is that it's often a good idea to find the background first and then to position to get the racer in front of it.
I also like to avoid having woods or trees behind the skier. That makes for a pretty busy background that usually detracts from the racer and often make AF difficult. Alpine skiing is specifically mentioned by Canon as being a difficult AF situation all by itself.
What this usually means is that it's good to find a headwall and then to shoot the skiers as they come over the top. If you're lucky, you get a nice blue sky with bright white snow and the skier. If you can catch them just as they cross block the gate, you can get it where the gate is bending as it goes down. Helps lend a notion of speed and power to the image.
Also, frame/crop as tight as you can. It's ok to cut off ski poles etc... I'm at work now, or I could post some examples.
J.