To keep track of the cards played in blackjack, players can use observation and memory techniques. Mentally noting the high and low cards dealt helps assess the remaining cards in the deck, focusing particularly on high-value cards like tens and aces. Some players adopt a simple counting system, assigning values to cards (positive for low cards and negative for high cards) to calculate a running count during the game. This method aids in making informed betting and playing decisions. It’s important for players to be discreet in their counting to avoid drawing attention from the dealer or casino staff, and practicing these techniques in low-stakes settings can enhance their effectiveness.