An add on to post 120:
When the skis are on your shoulder, make sure the bottom ski (will be upside down) is the ski with the brake forward of the top ski. If not, the top ski will be able to "ski" forward and they will come apart.
Your forearm/hand holds the top ski against the bottom skis brake. Most of the weight will be behind your shoulder so your arm presses on the front to balance them and hold the top ski against the bottom ski's brake.
I sometimes carry my daughter's skis also just for the extra weight. Since hers are very light (130's), once I have my skis on my right shoulder and being held by my right forearm, I'll put her skis in my right hand (I hold her ski's tips and they hang straight down below my skis). It acts as a counter balance and actually makes it easier to carry.