Low Post Action

[rwest]

This is my 2nd year officiating basketball. My biggest struggle and what I want to work on the most (at this point) is low post action. When the big guys are banging at each other, what do you consider too much? Both players are fighting for position. What do you look for in calling this foul? I've called it once during a game when I saw the player in front was forced to bend over at the waist.

Thanks!