Workout your legs (Quadriceps, Calfs & Tibialis Anterior) and core (Abs & balancing exercises) to prepare for your time on the hill. Low weight, high reps will build that "all day" endurance that you are looking for.
Pack ski clothes in your carry-on. This way if your luggage gets lost, you can still enjoy the mountain.
Eat a good breakfast. Supplement with Vitamin C and all kinds of Vitamin B for energy.
To avoid losing your gloves or mitts, utilize either the built-in glove leashes in your jacket or the leashes that come with your gloves or mitts.
Put energy bars in your jacket pocket or backpack and eat them as a mid morning snack. This will allow you to avoid the lunchtime crowds.
Remember to always drink alot of water when at high altitudes.
Never wipe the inside of your goggles; this will scratch the anti fog film. The best way to avoid goggle fog is to put them on and leave them on.
Keep a trail map with you on the slopes, preferably in an easily accessible pocket.
Check your snowboard bindings to make sure that they remain tight throughout the day.
LAYER ONE: The layer closest to the body provides insulating qualities and pulls moisture away from the skin.
MID LAYERS: Multiple layers of clothing. With proper high performance components, it traps your own body heat between the layers to keep you warm while skiing/snowboarding.
PROTECTIVE LAYER: The outermost shell fabric is the last layer which protects you from wind, rain or snow.
The purpose of wicking is to draw the moisture away from the skin to the next layers, which makes you feel warmer and more comfortable. Being wet makes you feel cold. When moisture has moved from the skin into (nonabsorbent) clothing, it will evaporate faster. Synthetic materials such as polyester and microfiber fabrics are good choices as they do not absorb moisture.