The interfaces people remember often borrow something from the physical world: a drawer that slows down before it closes, a switch that clicks into place.
Weight
Large elements should move more slowly than small ones. When everything animates at the same speed, the interface feels weightless and slightly fake.
Friction
A little resistance at the edges of a scroll or drag tells people they have reached a limit. It is far clearer than a sudden stop.
Restraint
Physical metaphors work best in small doses. One well-tuned interaction is worth more than a page full of bouncing elements, and everything should respect reduced-motion settings.