If someone knew the answer to this question he would probably be the richest man on Earth, and it would be the end of casinos. And casinos are doing pretty well, so it means no one knows it. In the competition “man against the spinning wheel” the heartless machine has it on the man. Because roulette is a random game. Of course the more bets you make, the more likely you win, but there is nothing like a guaranteed success. Still players try to beat the accidentality of the game. They make complex calculations, use the theory of probability, create more or less comprehensible systems.
Some try to share their systems with other gambling enthusiasts, recommending them and offering them for money. If these systems were so good why do they make their livings selling them, if they can hit the jackpot in every casino? It proves the effectiveness of these systems, or rather the lack of it.
The Martingale system is well known for making your chances for winning higher. Basically the player chooses one colour and keeps betting it consequently. When he loses he doubles his bet and plays until he wins, because according to this system the ball has to stop at the right field finally. It happens that the bet is getting higher and higher and the ball continues to miss the right colour. After the last bet, when you can’t double it, if you win you get only the amount equal to the first bet if a casino places limits on high bets.