Like most things it is down to general practice time and getting used to the movements and its timings.
I have began to realize, however, that a lot of guys tend to work less on the single elements but moreso of an overall thing. Whilst that's good for most productions, effects, flourishes or whatever, in this case I don't think it's the best of options. I found that many people's productions are actually too slow; mainly because they have not practiced one key element enough. That key element being the "
Reverse Finger Pass" of the single card in the right hand.
I'd say that is what makes the production look beautiful, and that can only be accomplished if an elegant and smooth Finger Pass is performed. So, I reckon the best way of practicing this is to feel comfortable with your Reverse Finger Pass, for then you'll find the rest of the production just fits into play and works in harmony.
Of course, other small details are also used to help paint the picture, such as hand twists (left hand included) and various other flicks, twists and turns. What I am saying is, just try to make sure you feel comfortable with the small elements that make the entire production -- only then will you feel comfortable and make the production appear outstanding. From there, it's just general practice-time; the fun stuff!
Hope this helps,
Jordan