French and some European Roulette tables also utilize what are known as French or called bets. These refer to certain sections of the Roulette table that represented by corresponding numbers and phrases on an ellipse. These are Voisin du zero, Orphelins and Tiers du Cylindre, and are based on a particular section’s proximity to zero. The numbers within the ellipse function in a similar manner. 

Another strategy that is good for more wary players is one known as the Paroli system. Here you make an initial bet of say £10 and if it loses you repeat the stake for the next spin. When your bet wins you double your stake for the next game and so on. If you then win three games in a row you should return back to your original stake. The thinking behind this system is that your luck will run out so it reigns in any outlandish bets before you get carried away.
On an American wheel, there are 38 spots: numbers 1-36, plus 0 and 00.  Your odds of winning a one-number bet are 37 to 1 (37 ways to lose, 1 way to win).  But if you win, the casino doesn't pay you 37 to 1, they pay you less: 35 to 1.  The difference between the true odds and what they actually pay you is 2/38, or 5.26%.  You can do this same calculation for the other bets, and it comes out the same.