The most important part of dressing for a ski trip is wearing layers. The first layer you put on is referred to as your base layer. This consists of a thermal shirt and pants. The material should be breathable and wick moisture away from your skin. Next is your mid layer. This can be a sweater, turtleneck or other insulating shirt. Stick to items that don't add too much weight. If you are skiing in a particularly cold environment, you can add a fleece or soft shell jacket as an insulating layer. Last is your ski jacket and pants. These come in two basic styles--insulated and shell. An insulated jacket and pants will do a better job of protecting you from the cold and other elements. A shell layer provides less protection and is more appropriate for warmer skiing climates.
When you go skiing, every part of your body should be covered for the best protection from the cold as well as from injuries. Thick ski socks or snowboarding socks will insulate your feet from the cold while also providing a layer of padding to protect against impacts. You also need quality ski gloves that give you a good grip as well as padding to protect against injuries. A helmet or hat is a necessity, and should cover your entire head, including your ears. A neck gaiter will cover any exposed areas beneath your hat and above the collar of your jacket. Snow sport goggles will protect your eyes from the snow and sun. Make sure that they provide UV protection.
If you don't ski very often, you may opt to rent the majority of your ski equipment. If you are going to purchase just one piece, however, your boots are the most important item to own. You will get a much better fit from your own boots than you will from rented ones. You can keep your boots in top condition by replacing the foam inserts every few years. Other ski equipment that you need includes ski bindings appropriate for your boots, skis and poles. If you are using your own poles, make sure that the bottoms are freshly sharpened before you hit the slopes.
If you are traveling to your ski location, a couple of specialized travel bags will keep your ski equipment in top condition. A ski bag for storing your poles and skis is essential for taking these pieces on an airplane. Check with your selected airline about other guidelines for transporting these items. A boot bag is also handy for transporting your ski boots. This will ensure that your boots are protected from damage on the way to your destination.