When card counting in blackjack, your bet should vary depending on the "true count," which is the running count divided by the number of decks remaining. When the count is high, indicating a favorable deck, you should increase your bet since the odds are in your favor. Conversely, when the count is low or negative, you should bet the minimum, as the deck is less advantageous. A common approach is to bet proportionally to the true count—betting more when the count is positive and less when it's neutral or negative. However, it's important to manage risk carefully, as even with card counting, there can still be losing streaks. Always bet within your bankroll limits to avoid significant losses.