Martingale is probably the most popular betting system in existence. It's simple and easy to use, simply double your bet on a loss and reset to your base bet on a win.

A martingale is any of a class of betting strategies that originated from and were popular in 18th century France. The simplest of these strategies was designed for a game in which the gambler wins his stake if a coin comes up heads and loses it if the coin comes up tails. The strategy had the gambler double his bet after every loss, so that the first win would recover all previous losses plus win a profit equal to the original stake --wikipedia


The basic martingale strategy is to double up your bet whenever you lose and to reset to your base bet on a win. For example:



Bet Amount
Bet Result
Total Profit


1
Loss
-1


      
2
      
Win
      
1
      
      

      
1
      
Loss
      
0
      
      

      
2
      
Loss
      
-2
      
      

      
4
      
Loss
      
-6
      
      

      
8
      
Win
      
2
      
      

      
1
      
Win
      
3
      
      

      
1
      
Loss
      
2
      
      

      
2
      
Win
      
4
      
      

      
1
      
Win
      
5
      


For these bets, a multiplier of 2 was used and the payout for the bet was also 2x the bet.

The most logical multiplier for a setting would be one that compliments it directly. For example, when playing at 33% chance to win, or on a payout of x3, the most logical mutliplier is 1.33.

There is also a strategy called reverse martingale. In a reverse martingale, you double up on a win and reset to base bet on a loss.