I own Bone's Anaconda DVD- it's something I have to practice everyday, otherwise my skill with it will deteriorate. My tips (from experience that work for me to say the least) :
1)Use new cards.
2)Keep a stable grip and execute the move gently.
3)In concordance with #2, do not apply too much pressure or the cards will spit out everywhere.
4)In flourishing, everyone has their own preferred way of performing flourishes. For each flourish, this is something you have to discover yourself over time, Anaconda is no exception.
I've been working on my Anaconda for nearly a year now and so far it's about 3 feet long on average.