You're not going to want to hear this (or maybe you will?) but the best thing you could do is go snowboarding more often. I used to ski way back when, and I only went 5-6 times a year. Never got very good. Now I snowboard, and I did 40 times last year. My progress has been WAY better, even allowing for snowboarding being easier (once you get past the startup). There's no substiture for hours on the mountain. Also, two days in a row is as effective as three days spread out.
I hate the parts between winter