I find it really helpful to watch how the best pros that stand a lot do it. Julian Alaphillipe is one of the best to watch as he rides standing more than almost any other top pro. His body is pivoting in very subtle ways, and the bike is also moving in sync with that, and the combination looks effortless.

I rarely stand myself, I can get the same watts for a lot less work on all but the highest zone of effort. I have improved at it over time though.