Let me be absolutely clear about one thing up front: studying past spins does not help to predict future spins. This is true in both land and online casinos. The reason I emphasize this is because roulette seems to be a magnet for con men selling get-rich-quick betting systems. Usually these betting systems are just a glorified Martingale, an early betting system based on doubling bets until you win. As with every casino game, all betting systems are equally worthless. The odds are the same on each and every spin. If the ball landed in red the last 100 times the probability of red is still the same as black the next spin. If you don't believe me here is what the Encyclopedia Brittanica says on the topic of roulette:

"The oldest and most common betting system is the Martingale or 'doubling-up' system, in which bets are doubled progressively. This probably dates back to the invention of the Roulette wheel, but every day of the week some gambler somewhere reinvents it, or some variation of it, and believes he has something new. Over the years hundreds of 'sure-fire' winning systems have been dreamed up, but regardless of what system is used, in the long run it cannot overcome the house's advantage of the 0, or 0 and 00. This house advantage is the only system that consistently wins in the long run."

Now that I got that off my chest let me talk about the odds of roulette. In the United States, most roulette wheels feature both a zero and a double zero. With this wheel all bets on the layout except one carry the same house edge of 2/38, or 5.26 percent. Also, every possible mixture of bets will also carry the same house edge of 5.26 percent. The only exception is the dreaded five-number bet on 0, 00, 1, 2, and 3. This pays 6 to 1 and has a house edge of 7.89 percent. Thus on the double-zero wheels it doesn't matter what you do as long as you stay away from the five-number bet.

In Atlantic City casinos, if the ball lands in zero any even-money bet (such as red, odd, and 1 to 18) the player loses only half. This cuts the house edge on the even money bets in half to 1/38, or 2.63 percent. The other bets are still 5.26 percent.

Single-zero roulette games also offer better odds than the standard double-zero game, and they come in two flavors. "Plain" single-zero games offer a house edge of 1/37, or 2.70 percent. European single-zero games follow the Atlantic City convention of giving half back on even-money bets if the ball lands in zero, and offer a house edge is 1/74, or 1.35 percent. Bodog offers the plain single-zero game, although they call it European Roulette.

Some casinos with the European rules may give you the option to "imprison" your bet when the ball lands on zero instead of giving you half back immediately. If you then win on the next spin you get the full amount back. However I advise taking the half back instead.

In American casinos, single-zero roulette is rarely found on the main floor but can be found in most high-limit rooms in Las Vegas and Atlantic City. Some of these games are plain single-zero and some are European. Some Las Vegas casinos with high-limit European roulette are the Bellagio, Mirage, Aladdin, MGM Grand, and the Wynn. The few American casinos with single-zero games on the floor post higher minimums, such as at the Stratosphere in Las Vegas.