Here’s the secret to Balatro, there are basically two strategies that work. Focus on flushes, or focus on two pairs.
Also, if you get that joker that makes all red cards the same suit and all black cards the same suit, then a 9 card hand always has a flush.
Likewise, two pair is extremely reliable, it’s hard not to have it. Just get a bunch of blue seals and pump that two pair up to level 20+.
Finally, cards that give you flat bonuses are fine, at least early on. But you really want cards that have increasing bonuses, that get better every round.
There is a hidden third option: focus on jokers, play high cards or pairs. The idea is that you get all chips from jokers so it barely matters if you play a 2 or an ace or whatever, allowing you to ignore pretty much every boss debuff. You try to get to a point where you have scaling jokers scoring the chips, with a setup like this:
The trick is that all of these should be scaling in the sense that their chips or mult go up as the game progresses, and that you need to play to that. Constellation, for example, gives you an extra x0.1 every time you use a planet card. See a planet card for a hand you never play (like any hand with more than 2 cards), you still buy and use it.