Help make movements look life-like?

Hark

One idea so far is, per every keyframe, slightly shiting angle.position of every body part, instead of leaving stiff.
A leg moving up and down will often move the entire body, in real life.

And, having 2 keyframes, left and right to the... main movement's keyframe, to enact such slight deviations.
So, when my mouse moves the positions thru main middle keyframes... the nearby left n right, are giving subtle movements too.