There is no such think as a 100% roulette strategy. It's only an illusion. People think because they can cover 80 - 90% of the board and show small profit compared to amount they wager that they figured out a system. But guess what even know your odds are greater to win at beginning of every spin.

The 3/2 plan is a bet on both bets at once. Three chips are placed on Red, Black, Odd or Even, and two chips are placed on one of the three columns. The theory is that enough numbers are covered in one spin to give the player a chance to make a profit.