A very subtle technique detail for the follower is that, when the follower kicks forward with her left foot, she pulls back with the left foot. The natural questions is, "David, how will I know to do this? Why am I doing this in this one position".

Going one level bigger, we can make the point that any time anyone dancing tango extends a leg forward, they pull the same hip backwards and they tighten their abs. This helps create contra body motion and extends the line.

And one level even bigger, the placement and facing of the hips in tango is really important. Often, a step can be executed with mediocre hip placement. But equally often, it doesn't feel good until the hips are where they should be and consciously involved.