I learned the move quite quickly and this was the main factor that made it work:
1) Don't be afraid to bend the deck, you'll need to bend them for them to glide back, and it will hurt your hands after practicing for a while because it does take some hand strength....
2) A new deck does work well as others have mentioned.
3) When you release, just do it gradually and when you get to a low number of cards, bring your hands back to smoothen out the motion.
4) The main thing is practice, I just learned how vital it is, personally, I got the move in a few days just because I sat down for about thirty minutes and did it...
Those are my few pointers, they worked for me, but no matter how many tips and tricks you get, until you sit and practice it, you won't get anywhere, I learned this the hard way