It can take time for someone who is used to handling paper cards to get used to plastic cards. One of the main problems people have when adjusting to plastic cards is managing the slipperiness of the cards. A specific problem that a lot of people encounter is squaring up the deck in a nice pile on the table. The top card will, seemingly of its own volition, try to slide off the top of the deck.
Fortunately, this is an easy problem to counteract. All you have to do is press down on the top card with your index finger as you’re setting the deck on the table. This forces the air out from between the cards, increasing friction between them. The cards will stay in a nice, neat, squared-up pack, with the top card remaining exactly where it should.