One subject that always comes up when people discuss winning at roulette or getting an edge is the topic of biased roulette wheels. To really find a bias in a wheel, you'd need to clock at least 4000 spins before determining a real pattern, and realistically speaking, you won't find a bias towards red or black. At best you'll find a bias toward a specific set of numbers.
Casinos don't want a biased wheel, because the house edge at roulette relies on the odds being 37 to 1 for each number over time. If certain individual numbers pay out more often than they should, the casino loses money. In this respect, a biased wheel isn't like a fixed game of blackjack, although casinos don't really have an interest in fixing any of their games, since the house edge is in their favor on all of them.
If you are able to find a biased wheel, and you've got a reasonable amount of confidence in the bias, you should bet individual numbers as much as you can. If you're in a rare situation where you have an advantage over the casino, you don't want to waste it on bets with low payouts.
Something related to wheel bias but that isn't exactly the same thing is dealer signature. Some roulette dealers have been spinning the ball for so long that they do it in exactly the same manner and at exactly the same speed every time. This produces a situation where some numbers might come up more often than other numbers.
Usually if you're looking for this type of advantage play it's best to find an older dealer who looks really bored, like they've been doing this a long time. You don't want someone who's really young and just learning how to spin the wheel. You want someone who's spun it so many times that it's become automatic and predictable.
Since it would take about 4000 spins to determine with any degree of certainty any patterns on a roulette wheel, it would take a considerable amount of time to track that many spins. Maybe 100 hours or more. Realistically speaking, you might be better off learning to count cards or play poker really well instead of trying to get an advantage finding a biased wheel or a dealer with a signature.