Always create a 21 when you have the chance to. Keeping as many open columns as possible reduces your chance of having to discard.

The closer a pile gets to 21, the fewer the cards that can be played there. If all your piles are close to 21, you run the risk of having to discard several cards in a row.

Remember that 16 of the 52 cards have a value of 10 (about 30% of all the cards) so try to create columns with 11 in them, which will combine with any 10 to form a 21.

Group your low cards together, if you don't need them, to form Five Card Charlies, which give you the most points for a column-clearing. But don't go out of your way to make Five Card Charlies, or you'll deplete your supply of low cards that you need to clear those columns with 17, 18, or 19 points.

There are only 4 aces; try to keep track of how many you've seen so far.

Similarly, try to remember how many of the two Black Jacks are still left.