Roulette is a pure luck game and no strategy exist for it unless you try martingale and back to base bet strategies like dice.
In Casinos there are actually people who try and do martingale. And you can easily see their face turning red, when they lost like 6-7 times in a row. Most eventually walk away and the next roll would of been a winner for them.
Lesson learned though. That's why i never using martingale strategy on provably fair casino like dice sites or roulette. it's so risky, for me better pick red/black on roulette. When you lose change your colour.