Staying warm is the primary consideration in deciding what to wear when you go skiing.
All else is secondary.
A friend who happens to own a ski resort says, "There's no such thing as bad weather, just bad clothing."
Basic principles: Choose fleece over cotton; wear air-trapping middle layers; cover everything with a windproof layer; make sure head, face, and hands are covered as well. Remember as well that it is easier to take off clothing if you are too warm, than it is to add something you don't have.
Another friend whose life essentially spans the history of modern skiing in New England likens himself to the Michelin Man when he is fully dressed for the slopes. Layer upon layer of clothing protect him from the cold. "Stay warm, go skiing, have fun," is his motto. We'll talk more about layering in a minute.
First let's at least acknowledge that fashion plays a part in choosing ski wear. It's below warmth in the priority list, but how far below depends on the skier, and on the circumstances. Are you a fashion maven? Go for warmth with style. Are you going to a social event on the slopes? Again, go for clothes that look good while they keep you warm. Are you a die-hard skier who hits the slopes early and often, skis 100 days a year, and beats up on your clothes? Go for ruggedness as well as warmth. Do you go for the après ski? Then fashion comes first. Decide honestly what you need in clothing, and go for it. Remember though, that fashion means money.
OK, back to layering. This is the secret to staying warm and dry and comfortable in the worst conditions. Begin with fleece long underwear, top and bottom, and ski socks. Add either ski pants or bib, or warm pants and warm shirt or turtleneck. Next comes parka, or fleece jacket and wind shell. Finish off with hat, gloves or mittens, face mask in extreme cold, and goggles. We suggest a helmet as well, for safety and for warmth.
What you wear will change with the season. December and January can be bitter cold; days start to warm a bit in February; by March, spring has sprung and chances are you will be skiing at times in very little.
A final piece of advice: Dress as if the chairlift is going to break down when you are sitting at its highest point, dangling in the cold winds of winter. It probably won't, but if it does you will wish for the warmest clothing you own.