signature moves

as a guard i tend to do pull up jumpers
but now i was put in as a post
i am not sure but pump fake at my taller opponents
or jab step in order to drive or pull up
what are the most important post moves that i need to learn in order to be successful at 5 foot 9?

The most important thing is to pick a base (go to) move that you're really good at, and then a counter when that move gets taken away. That is a simple a very effective way to score in the post at all levels of play.

An example would be:
Base move: front pivot jump shot or hook.
Counter move: step through

The actual moves you pick depends on what you're good at. Some players like to face the basket first (use a reverse pivot). Then look to shoot or counter.

Develop a really good go to move that is tough to stop. Then try to develop a counter that compliments that move.

If you want to learn more and get into more detail, here are a few good resources to consider (they are cost money):
https://www.breakthroughbasketball.com/pr/post-play.html
https://www.breakthroughbasketball.com/pr/attackandcounter.html
https://www.breakthroughbasketball.com/camps/#attack