If you have skis that are heavy and stiff enough, start by imagining every pile as an enemy. It MUST be destroyed, attack it. Full commit on downhill leg and go. Rip through them, turn through them, make them not so fluffy anymore.
If you want to have more of playful approach learn to pivot. This works a lot easier with rocketed soft tip and tail skis, try to skid/slarve through every pile. To practice you can ski any spine like snow(side of the groomer) and try to make a spray of snow flying off the spine on every turn, turn release edge, turn release etc
As practice goes ski as much trees and irregular snow as you can. Afternoon destroyed refrozen groomers are great. The more it hurts the better, ski snow you hate.
Lastly fitness. Or maybe this is the first thing? many people can ski many hours on groomers(because it is easy once you are an intermediate) but are done after few runs of bad chop. How to get more fit? Doing stairs, both up AND down, you have to go down this is the absorption you need. If you live next to ski resort see if they have trails there, do loops on those, first walk down then run down, trail running is an amazing training for skiing, you learn to absorb shock, your knees and ankles get ridiculously strong and you get fast and more balanced. It is also very fun, running downhill on technical trails is similar to skiing tree lines, mental state and flow are almost same for me at least.