The essential tip to play and win 21 Puzzle card game is to always know the value of each card off the top of your head. Keep counting the value of your cards to reach the 21 score before other players. You can also use the strategy of making an 11 in the game. This way, it will be easier to make your score 21 as you can easily find a 10, J, Q, or K that carry 10 points.