The straight answer to "How to play roulette effectively?" is found at the wheel. Roulette looks like pure chance, and it is, but the rules still decide how much any bet costs. A European wheel has one green zero, an American wheel adds a second, and French tables add rules that return half of some losing bets. Knowing which wheel is in play, what each bet pays and what the zero takes is most of what there is to know about playing roulette sensibly.
Speed matters as much as the edge. A busy live table manages around forty spins an hour, while an automated wheel or an online game can run several times as many, and each spin charges the same percentage of whatever is staked. Whether roulette is worth playing depends on treating that cost as the price of entertainment: at a slow table a fixed budget lasts an evening, at a fast screen the same budget can be gone in minutes.
No strategy can beat roulette, because every spin is independent and every bet carries the same edge. Betting systems change the size and rhythm of stakes, not the odds, and no pattern makes it possible to predict the next number. A player can still be good at roulette in a narrower sense: choosing a single zero wheel, sticking to a budget and knowing when to stop is how to play roulette effectively. Can anyone really win? In a session, yes; over many sessions, the edge does the rest.
The best odds in roulette are on a single zero wheel, and better still under French rules. European roulette keeps an edge of about 2.7 percent; French tables add la partage, which gives back half the stake on even money bets whenever zero lands and so halves that edge on those bets. French layouts also take call bets placed by name, such as the neighbours bet on a number and the two either side of it on the wheel. Knowing how to play French roulette mostly means knowing these extra rules.
Short answers
How are roulette wheels and balls kept fair?
Licensed wheels are tested and balanced, results are logged so bias would show, balls are made to a standard, and electronic machines use checked random number generators.
What are the odds of the ball landing on green?
On a single zero wheel the chance is one in thirty seven, and on a double zero wheel one in thirty eight for each green pocket.
What are neighbours bets and other call bets?
Call bets are placed by name on French layouts; the neighbours bet covers a chosen number plus the two pockets either side of it on the wheel.
Why does the speed of play matter at roulette?
Each spin charges the same share of the stake, so a live table at about forty spins an hour drains a budget far slower than a fast online game.
Does red or black come up more often?
Neither: each colour holds eighteen pockets, streaks say nothing about the next spin, and zero counts as neither, so even money bets lose on it.