New Blackjack players often make several key mistakes. They frequently neglect to follow the basic strategy, which involves making decisions based on mathematical probabilities. This leads them to make poor choices, like hitting on stiff hands (12-16) or standing on soft 17s, both of which can increase the risk of busting or missing opportunities to improve their hands. Many beginners also fail to understand when to use powerful moves like doubling down or splitting, or they misjudge the importance of the dealer's upcard. Emotional decisions, like chasing losses or taking insurance, are common and can lead to bigger losses. Additionally, poor bankroll management and an overfocus on side bets can detract from the core strategy and reduce overall chances of success. Staying calm, sticking to optimal plays, and managing bets wisely are crucial for new players to improve their game.