The biggest thing outdoors, in the cold, is dress warm, I bought one of those big heavy pair of pair of hunter's pants camouflage and everything. If you do layers, I usually go out in sweat pants under lined pants outerwear. I want to make sure that if I crouch for a shot I can hold position for 10 minutes even if I'm kneeling in the snow. Get some
Grabber Warmers, and take them for your boots and mitts. Wear a big oversized pair of felt lined boots that come at least half way up your calves and squish some activated Warmers up into the toe. Wear a thin pair of gloves inside your mitts to separate the warmers from your skins. Activate the warmers before you leave. Being able to warm up cold fingers is absolutely essential. Wear over size mitts attached to your jacket to hold the wamres that you can slide your hands into and out of easily. I wear a photographers glove on my right hand, with a thin wool glove and Warmer inside it. That will let me work in even the coldest weather without having to put my hands in and out of mittens.
My gloves are pretty thin, I can press the shutter release without opening them up. But if needed I can pop the top off my index finger and thumb without removing the glove, meaning my hand is always covered even if the finger aren't. IN cold weather there absolutely have to be warmers inside these gloves. There are also electric gloves available.
Wear enough clothing that you'll need to unbutton your coat while walking. When you get to where you're going to shoot you won't be keeping yourself nearly as warm, so zip up as soon as you stop walking.
Anyway, that 's how I approach these things.
You also might want to research what shooting mode you plan to use. Audiobomber posted his BiF settings in thread a while ago. I set my camera up in front of the computer, and they worked well on my Snowy Owl images, but i can't remember exactly what they were. I'll have to look them up again before next time I go out.