The best bet size progression for card counters is designed to maximize winnings when the deck is favorable and minimize losses when it's not. The core idea is to adjust your bets based on the true count, which reflects the number of high cards left in the deck. As the true count increases, you gradually increase your bet size. For example, a common strategy is to start with a base bet when the count is neutral or negative, then double or triple your bet as the true count rises. Some counters use more aggressive systems, like the Kelly Criterion, which adjusts bets based on your edge and bankroll, but this requires a more sophisticated understanding of the game. It's important to vary bet sizes in a way that doesn't draw attention, especially in casinos where large fluctuations can raise suspicion. Generally, the key is to bet more in positive counts to maximize your edge while minimizing risk and avoiding detection.