One tip regarding doing a snowplow with skis on:

 It's important to usually angle your skis while doing this a little towards your body. Why?

Because often there is snow buildup on the outsides of your skis away from your body. So, angling your skis toward your body down allows you to slide over buildups of snow especially from others ski tracks so you don't fall down needlessly. This way the outer edges of your skis away from you are slightly up because the metal edges towards you are gripping the snow more and give you more control of your skis that way especially in turning while snow plowing. If you tilt your skis downward away from you then this is going to make the outer metal edges grab the snow and likely you will fall down in the process. You want the metal edges towards your body to grip the snow not the outer metal edges while snowplowing.