A longer telephoto lens, and most importantly a camera that can shoot in RAW mode. Exposure of the snow is really hard, as the exposure washes out all the detail of the snow, especially on a sunny day. Most of what we see in your sample is just a white blob and almost no detail of the shape of the hill. In RAW mode you can import the image in to a program like Photoshop, or the camera's utility program. Shoot everything in RAW mode. Then post process it to get the snow detail.
Of course getting on the slopes and shooting action takes it to another level. You will need to be able to ski as fast as them and not fall, use no use poles, while skiing backwards. So for most people is comes down to the angle you shoot them from.
Exposure is a very tricky thing with snow. Most cheaper cameras just blow it out to a RGB value of 255 255 255 or close to it. That is just pure white, and it should be no higher than the mid 240s.
Go look at the samples of skiers in magazines or on the web, and look at the detail in the snow, and the angles the pros used.
You picked a difficult subject to photograph. Get the kids to take up water skiing, it is easier to photograph!
