In blackjack, the dealer's upcard significantly influences your decisions. When the dealer shows a weak card (2-6), they have a higher chance of busting, so it's often best to stand if you have a hand of 12-16 and let them take risks. You may also double down with strong hands like 9, 10, or 11. On the other hand, if the dealer shows a strong card (7-Ace), they are more likely to make a good hand, so you'll need to play more aggressively. In this case, you should consider hitting on hands between 12-16 and be cautious about doubling down. With a hand of 17 or higher, standing is typically your best option. A dealer’s Ace increases their chances of finishing with a strong hand, making it necessary to be more conservative in your decisions. Overall, your strategy should adapt based on whether the dealer's upcard is strong or weak.