To win online roulette - you need to play with your head not your heart. Throwing huge piles of chips across the board is a certain way to lose. To be honest under normal circumstances roulette is not usually the best returning game at a casino. It's advantages are it's easy to learn and you can play at your own pace - but perhaps most of it's just fun.
Albert Einstein had an opinion about how to win at roulette - "steal money from the table when the croupier is not looking"
There are two main types of roulette wheel - the European and the United States wheel. If you have a choice always choose the European one as it has a single 0 compared to the two of the United states. The house edge (advantage) on the US wheel is more than 5% due to the extra 0 - on a European wheel it's nearer 2.7% although this can vary slightly depending on which rules are followed. Obviously you have a much better chance of winning on a European wheel that an American one.
If you're looking for how to win at online roulette you need the very best odds on any roulette wheel, you need to find a couple of things - firstly as stated above winning at roulette you should be playing on a European wheel. Next you need to find a casino that offers the 'en prison' bet - this basically means if you make an even money bet and the ball lands on a zero then the bet is held on the table for the next spin. If the bet wins the next spin - you get your stake back if not it is lost. This simple rule actually has a significant mathematical impact in the odds - the house edge is reduced to 1.35% in these cases - so the best value odds are even money bets on these types of tables.