Let us first establish that there is no guaranteed system for winning at Roulette but it is good to know what your odds of winning are. As Casino games go, Roulette gives you a pretty good chance. The simple sums are that there are 37 numbers in European Roulette and a winning number pays out at 35:1 plus your stake remains on the table which gives you a bet return of 36. This point about the stake remaining on the table is an important one as without that in mind you will not understand that all bets on the Roulette table have basically the same odds. I was playing on a cruise ship some time ago and placing bets on a split (two adjacent numbers on the table) when a French player told me I was stupid to do that as I should place a separate bet on each number which would give me better odds. His rationale was by placing two chips on the split I was getting odds of 17:1 making 34 chips for a win whereas by placing on a single number I would be getting odds of 35:1 or 35 chips for a win. I was in no mood to argue the point and my French is not good enough anyway but the point to remember is that the stake remains on the table and is available to be re-bet or withdrawn. When betting on the split my 34 chips win needs to be added to my 2 chips stake making 36 chips available to me. When placing a one chip bet on a single number I win 35 and add my one stake which also makes 36 chips available. In other words there is no difference. The same logic will apply no matter what bet you are making (see the how to play section for possible bets and odds).
One thing that will reduce your odds of winning is playing American Roulette or any other Double Zero game. By having both “0” and “00” on the wheel your chances of winning have gone from 1 in 37 to 1 in 38 but the odds paid are still 35:1 for a winning number.
The best of luck.