Pinning down "How to play roulette effectively?" is done 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 well.
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 its work.
Roulette odds come straight from the wheel. On a European wheel there are thirty seven pockets, so the chance of landing on green is one in thirty seven, and on a double zero wheel one in thirty eight. Red and black each hold eighteen pockets, and neither color wins more often over time; a streak of one color says nothing about the next spin. The color rules are simple: zero counts as neither red nor black, so even money bets lose whenever it lands.
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.
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.
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.
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.
A European wheel has a single green zero, an American wheel adds a double zero, and French tables use the single zero with rules returning half some losing bets.