Only draw from the Discard Pile when it completes a run
Instead of drawing a card that you know won’t make a meld, try drawing from the StockPile instead—it may complete a run for you! Additionally, drawing cards from the Discard Pile may give your opponent clues about what kinds of melds you might be going for (and they might think twice before discarding something that helps you!)

Discard higher value cards rather than lower ones
The objective of every round is to build a good hand that you can knock with, which means finding ways to lower your deadwood score. Of course, you should make melds whenever possible; if you can’t, it usually makes sense to discard cards with higher values.

Watch what your opponent puts in the Discard Pile
Every card that your opponent discards is a hint—if you can discard cards that are close to what your opponent discards, they are usually not going to benefit from taking them. A bigger advantage of paying attention to the Discard Pile is that it gives you information about which cards still remain in the deck!

Watch what your opponent draws from the Discard Pile
If you know which cards your opponent is looking for, you can gain an advantage by holding onto cards that they are trying to collect. It might make sense to hold onto a card your opponent needs and get rid of it when you knock to complete the round.

Hold onto high pairs early in the game
Most of the time, players will discard high cards to lower their deadwood so they can get closer to knocking; by holding onto high pairs, it is possible that you will be able to complete melds with these cards. As the game continues, the risk of holding onto high cards increases, and they should probably be discarded before the round progresses further.

Know when to knock early or hold off
Knocking early in a round means that it is less likely that you will be undercut by your opponent—and may also mean catching your opponent with more deadwood for a higher score! Even knocking with 10 early enough can be a very strong move. The longer the game has gone on, the better your hand should be to knock; if the deck is halfway gone, it is likely that your opponent has gotten rid of most of their deadwood and may undercut you.