Roulette is perhaps one of the simplest games to learn how to play because it is a game of 100% pure luck and there are not an overwhelming number of odds differences. Although, there are some differences that make payouts larger (on say, hitting a specific number), rather than hitting on a "red/black" type of bet.
Therefore, it is possible to have a strategy -even though it is a game of pure luck. Basically (just like with Craps), you can "hedge your bets" by betting small on the big payout bets and betting a little larger on the smaller payout bets. The whole idea is basically to diversify in a way that you increase your odds of winning enough on each hand (or not losing too much) to stay in the game round after round.
Over time, the winning Roulette player will come out ahead by keeping focused and winning the occasional big payout (usually the profit) while staying in the game on the small payouts.