First - There is no guaranteed way to win ANY game of chance (anyone trying to tell you otherwise is just blowing smoke up your exhaust pipe).
Second - Roulette is a game of chance.
Mo's answer is actually quite complete. Another way to look at it is that after you loose your first bet (say $20) you are risking $40, then $80, $160, $320, $640, $1280, etc. just to be $20 ahead. As Mo (paraphrasingly) said, betting in geometrically increasing rates to break even is the fastest way to go broke (and after the fourth or 5th increase, that first $20 bet is pretty insignificant). Except for perhaps ESP, there are no skills that can change the probabilities.
If you enjoy games like this, try an opposite tact - your odds of winning will be lower, but you risk much less money: take a limited amount of money with you (say $1000) for your roulette bankroll. Then, on your first bet and any bet after you have lost the previous bet, bet your minimum. IOW, if you take $1000, that means that you have 50 $20 bets, 100 $10 bets, etc. Then, any time you win just bet your previous payoff (previous bet plus winnings). If you do this, at least your losses will be under control and IF you can win many times in a row (enough to have more on the table than the max bet) then you pocket that money and you could possibly come out of it a winner, and if not then you have only lost at most a set amount of money (assuming of course that you leave the table after having lost your committed bankroll).
There is one way to be a guaranteed winner at roulette, craps , baccarat and other games of pure chance: don't play them, and you can count all of the money that you would have bet as winning. In any game where your opponent (the house) has winning odds, they always win in the end. After all, who do you think pays for all of the opulence of these casinos, and the billions of dollars to develop one casino resort? If there was a system to win all casinos would be broke by now (or at least not spinning the roulette wheel).
Now, this does not necessarily apply to games that are games of both chance AND skill, including blackjack, gin rummy, bridge, poker, etc. BUT, with many games of skill you are often playing against skilled opponents (not the casino), and if your opponents' skills are much higher than yours, you are actually better off (in the long run) playing games of pure chance - i.e. lack of skill = big loser (almost all the time).
WARNING: NEVER EVER EVER gamble with money that you need for something else (food, rent, etc). Stories of people that win that million in one shot are much much more frequent in movies, TV and the like than in real life. Envisioning it will not cause it to happen, no matter how much you "try." It's all BS - believe me, I know!
Anyway, as you can see I love to write, but not about this anymore. Best of Luck!!