Being able to monitor the cards your opponents are discarding and picking up is another important skill in the art of card counting. You can then modify your straall slotstegy based on your increased understanding of the sets and runs they might be attempting to form. You can also tell which cards are likely in your opponents' hands or the draw pile by keeping an eye on the cards that have already been played. An essential part of playing rummy well is making good use of the discard pile.