Common betting systems for blackjack include strategies like Martingale and Parlay. The Martingale system involves doubling your bet after each loss, aiming to recover previous losses with a single win. Conversely, the Parlay system focuses on increasing your bet after a win to maximize potential profits on a winning streak. Other systems, like the Fibonacci and Labouchere, utilize different sequences and patterns of betting adjustments based on wins and losses. While these systems can add structure to betting, it's essential to remember that no strategy guarantees success in blackjack, as the game still relies heavily on luck and the house edge.