No betting system is good for online roulette players. People tout the Martingale System or other progressive betting systems like the D’Alembert, Fibonacci, and so on. All of these stipulate betting more money after a losing spin on the assumption you’ll win back your losses and then some.
Once computers could analyze billions of roulette spins, mathematicians proved that the Martingale System and other methods do worse than flat betting. They don’t work.