For me it depends on the consistency and depth of the powder. If it's really deep, I ride in the back seat and sort of ride it like a surfboard, making initiations from putting pressure on my back foot. In less then a foot of powd or windblown, I ride it much more like you would a groomer, initiating turns with my front and generally leaning forward in an aggressive style. If you try to lean forward in deep powder, you start sinking and lose speed unless you find yourself on a very steep incline. Speed is almost everything in deep pow, you want to generally keep your speed as high as possible.
PowderHound and TreeNinja