Outside bets in roulette carry the lowest risk. They cover more numbers yet the payouts are lower (1/1 for Red, Black, Odd, Even, 1 18, 19 36). These outside bets carry the best prospects for long-term wins.
The real trick to roulette is to get lucky, then quit while you're ahead. Every spin has a 1 in 37 (for European) or 1 in 38 (for American) chance of landing in a given pocket.