Roulette is a pure luck game and no strategy exist for it unless you try martingale and back to base bet strategies like dice.
Martingale is hard to use in roulette because there is so much number that possible to be hit. May be if you keep playing on red or black it will work but usually people try to aim big odds so they will be paid good amount
As my experience in roulette i never win in this game because of many numbers thats possible to bet it all because you will still lose even you are win..
Making a strategy in this game is hard because of many number to choose.. never win in this game .. i think there's no strategy for roulette but if you are lucky you can make more profit.. but not all can be win..