some things you missed out:
use all the joints to aim not just the limb your using, this can be the difference between kicking his arm off and getting a decap ive found.
its not just about how hard you hit him its also about where you hit him, for example a kick to the neck may get a decap whereas a kick to the face might not.
use shift+space to time your moves so that you hit him in the exact right spot.
use "E" at any point in a replay to edit it.
u should probably edit these in