Top online roulette strategies for big wins include the Martingale system, where players double their bets after losses, aiming to recover previous losses with a single win. The Fibonacci strategy follows a sequence to determine bet sizes, promoting a more conservative approach. The D'Alembert system balances risk by increasing bets after losses and decreasing after wins. Additionally, focusing on outside bets, like red/black or odd/even, can enhance winning chances. While no strategy guarantees success, understanding these methods can help players manage their bankroll and maximize their enjoyment of the game.