Practice? That's a good tip, sure, but, what if they don;t understand the correct technique quite yet, then practice is BAD. Practicing incorrect technique is never a good idea, because it is really tough to "unlearn" a poor technique in anything really.
I feel it is critical to make sure you have proper technique in place before getting into hard core practice sessions with any task. Cardistry, guitar, Swninging a baseball bat, Golf, or anything that requires proper technique to execute properly.
So, once you have the correct technique down, THEN practice. Find that sweet spot Warped talks about and examine the mechanics of the move carefully and patiently before practicing it 600 times...