If it's sport you can use analysis and for casinos martingale is the oldest known strategy out there...
NEVER use martingale as a betting strategy!
In the long run it's impossible to win, no matter what you try, when you make your bets, how much you bet, and when you take your wins and losses, there is no escape from the laws of probability! The exponential betting for a martingale strategy will make sure you will at one point have to bet 1 million to earn 1$ and not lose $1,048,575.
And that's for 20 times in a row, there are multiple casinos that will not let you bet over 10,000 or even 1000, which means you're stuck after the 9 loss, and there are multiple instances when for example red at a roulette came in more than 20 times in a row.
Martingale will always end with you losing!