What are the key principles in the optimal Gin Rummy strategy? The best play lies in remembering the discards, so that no attempt is made to form a set that is impossible or difficult to make because all or some of the required cards are buried in the discard pile.
It should be appreciated that a combination of h6 d6 d5 affords four chances of a set with c6 s6 d4 and d7 whereas cA dA d2 affords only three. A holding like d8 d74 s10 s8 s7 affords six chances of a set, including one of four cards, and whichever set is formed, two matching cards can still be kept.
A sequence is more valuable than a set of three of a kind, as more cards can be added to it, two immediately at each end of a sequence, one only on a threesome. The cards the opponent takes from the discard pile, and the cards he discards, should be noted to form a picture of his hand.
Cards which might help him should be kept both to block him and to afford laying off opportunities should he knock. Other things being equal it is better to hold low cards than high cards, so that any adverse score is kept down and also because they afford opportunities to knock. Most gin hands are won on two sets and three or four unmatched cards.
The early discards tend to be high cards, and it is often worth holding potential high-card sets early in the game. If such sets are not formed after four or five discards, however, they might be expensive to hold. The longer the game continues, the more wary a player must be of knocking with a high total of unmatched cards, as it is likely that his opponent might undercut him. It is not usually good policy, when it is possible to knock, to hold on hoping for gin. Use the correct gin rummy strategy, and you will win much more often!