There is a strategy in tic-tac-toe for never losing, but it doesn’t guarantee a win as either noughts or crosses (since the other person can always use the strategy for never losing too).
Poker and 21 are both games of odds. It is possible to have even odds in poker if you bet exactly based on the cards showing and ignore the behaviour of the other players. It is possible to improve or reduce these odds by anticipating or bluffing the other players.
In the right circumstances, it is possible to have slightly better than even odds in 21, but it relies on knowing what cards have been dealt over a long period of time.
Hmmm…good tips!! I guess they wouldn’t really be much of a game if you could always win. Other people are unpredictable but, as Drew said, you can work out the probabilities of things and play accordingly to heighten your chances of success!! 🙂