Flare
Passing the threshold (so, at approximately 50 ft) shift your visual focus point a long way down the runway.
In that way, your peripheral vision will show the descent rate.
Flare enough to almost stop the descent rate.
Do not switch your vision point to inside anymore, because that will destroy the continuity of your descent rate estimation.
My experience is that every landing that was less than soft, I had not shifted vision far enough down the runway, or I did something like a quick check of airspeed during the flare.