A good ski jacket is a must for all snow sports. You need to be warm and protected from the wind, rain, and snow while not feeling weighed down. The most important things to consider when buying one are warmth, breathability, and layering.
You should always keep the classic "three layer system" in mind when looking for a ski jacket and other ski clothing. In this system, the first layer is thermal underwear, the second is a fleece jacket, turtleneck sweater, or other shirt and the third layer is the jacket. The weight of the layers should depend on the climate and time of year in which you ski.
Some spring skiers may opt for a ski vest rather than a jacket for the final layer. The three layer system is designed so that layers can be removed throughout the day depending on the temperature and wind/water conditions as well as the skier's comfort level. It is better to start out a little too warm and remove layers than to not have enough warmth and protection from the elements when you need it.
A less insulated ski jacket is often less expensive than a more insulated ski coat, but it is unsafe to skimp on warmth if you really need it. If you will be skiing in very cold weather, consider getting a very warm jacket with good insulation. People who are concerned about breathability in a heavily insulated coat should consider a style with zippers at the armpits. You also should look for breathable, yet waterproof fabric in any type of ski jacket. Choosing one in a modern, yet classic style rather than a highly trendy style will keep you looking great for years. You can always wear trendy gloves, sunglasses or hats.
The third layer is called the shell as it provides a waterproof, weatherproof exterior that protects you and your other layers from wind and precipitation. When buying a ski jacket, make sure that the waterproof fabric covers the zippers and other fasteners. If the coat is highly waterproof, then it is also usually very windproof as well.