Most people think roulette systems and roulette strategies are the same thing. They are actually two quite different approaches to playing roulette.
First, let's look at playing a roulette system.
When playing a roulette system, you are following the rules of that system in regards to your betting and chip placement, which in columns roulette strategy theory, will give you an edge in the game and affect the outcome in your favor. (although, 99.9% of the time, it's the exact opposite that occurs)
Now, let's look at roulette strategy.
When using a roulette strategy, you play by a formula that is not set in stone, but is merely a guide as opposed to a rule. You take the system under advisement, but in the end, the decision of how to act is your call. A roulette system can be used as a roulette strategy, as long as it is played by this method.
One of the best pure strategies you can use when playing roulette, or any game of chance for that matter, is to set time and money limits for yourself.
For a time limit, basically what you want to do is pick a certain amount of time to play with, we'll say 1 hour as an example. When the hour is up, whether you're winning or losing, you call it quits for the night. As always though, the time you set for yourself isn't set in stone. Sometimes you might feel you should quit before the hour is up. Sometimes you might feel it's o.k. to go a little over the hour. This is where you would look to yourself to make a judgment call. Remember to play it smart though. Usually, the smart call is to quit while you're ahead.
For a money limit, what you want to do is set a limit on how much money you're willing to lose and how much money you want to win. When you hit your limit, call it a night. Remember though, this is a guideline, not a rule. As always, the final call is up to you. Use your judgment, and play it smart.
A variation on this strategy is if you hit your loss limit, walk away as usual. Your win limit is a little different. First, you make your initial win limit the same amount as you set for your loss limit. Once you hit this limit, you pocket your initial funds, and play only with your winnings. This is now round two. You set another win limit for yourself, and your loss limit is now based on your initial winnings. If you hit it, you'll break even instead of actually losing. (because you pocketed your initial deposit) Again though, in the end, play smart and make a judgment call. The final decision is always yours. The outcome can never be predetermined.
Another variation on this, is to use a casino bonus strategy. Most casinos will offer a bonus on your initial deposit. For example, you deposit $100 and they'll add $100 on top of that for you as a bonus. Now you're playing with $200 and you only deposited $100. What you want to do here is make a deposit at a casino that offers a bonus and only play with the bonus money. If you lose with the bonus money, you break even, so there's no risk as long as you're playing smart. If you win with the bonus money, pocket your initial deposit, and keep playing with the bonus money. Now you actually have a chance to cash in huge with 100% free money and absolutely no risk to your bank account whatsoever.
Finally, the last strategy I want to mention is to always play on a European table as opposed to an American table. The reason is European tables have only one 0, where as American tables have 0 and 00. 0 and 00 are put into a roulette table specifically to give a casino an edge because they don't count with any of the outside bets. (red / black, high / low, columns, dozens, etc.) With the European wheel having only one 0 as opposed to the Americans 0 and 00, it puts the odds a little more in your favor.