We used to do this teaching in ski school. It’s a simple test.
Stand up, close your eyes and lift up your left leg and balance on your right leg.
Repeat the exercise for balancing on your left leg. One of these will feel easier and you can balance longer before putting your foot down.
Most people are right leg dominant. Hence their left turn in skiing is better than their right (we want to shift our weight to the outside of the turn; so left turn most of the work is being done by the right leg). 
