Basically you should increase the accuracy of predictions, to beat the unfair payouts referred to as the “house edge”. If you’ve obtained no idea what I’m referring to, study the basics of successful roulette. If you find that material too superior, begin by studying what the odds are in roulette. If dealers really could do this, it might be easy to have a confederate play, causing him to win, and inflicting other gamers to lose, to make up for it. As long as they had been following correct procedures for the spin, and didn’t appear with the confederate in public, it would all look completely legitimate.