Avoid drawing cards from the discard pile unless you’re completing a meld- it will alert your opponent of the possible combinations you are going for.
Keep Middle Cards for more options: The middle cards give you the most options to create a 3 or 4 card meld and even if you don’t, they are low enough in value that it won’t be too costly. Eg: 7 can be used for most combinations from the deck.
Use Card Triangles: A card triangle is a set of two consecutive cards from the same suit and another card of the same rank as either of those two cards.
Time your Knock: If early on in the game, it’s safer to knock first. Later on in the game (after about 10-15 turns), don’t knock with deadwood of 8-10 because you risk being undercut.
Hold on to high value pairs at the beginning of the game.
If you have an ace as deadwood, it’s better to wait for GIN or Undercut than Knock.
Keep track of discarded cards– usually the cards that are close to your opponent’s discarded cards are safe to discard yourself. Also, you can eliminate possible melds based on the cards that have been discarded. For example: If two 10s have been discarded, no point keeping a 10 in your hand unless part of a meld.