In blackjack, it's generally best to always split Aces and 8s. Splitting Aces gives you a good chance of creating two strong hands, potentially leading to a 21 or 20, while splitting 8s improves a weak hand (16) by giving you a better shot at winning both hands. These moves maximize your chances of success in most situations, although there are rare exceptions depending on specific game rules or dealer upcards. However, for the vast majority of cases, splitting Aces and 8s is the correct strategy.