Well...personally I try to get a feel for where the movement is going, where the limb/body/whatever was first off, where it is now and where it went inbetween. Often this will come through in a sketch as construction lines, movement lines and other ghosty scribblings.
For example in the boxer hitting the guy at the top right of my first page of sketches there a line running from his fist through the the other guy and back to the left.
That's where his fist travelled.
There's also curved lines running up the spine of both guys, in the guy who's been hit it's because his head has been forced across.
Often these lines don't really correspond to something physical in the picture but add to the effect. Often they key in the main axis of the figure (spine, across shoulders, arms, across hips etc).
These sorts of curves are really important.
In your Thai boxer I see a main curve through the kicking leg and up the spine, another one down the arm, another up the support leg. Get those curves acting dynamically together and what you draw over the top (the structure, the clothing etc) will then have the movement underpinning it.
Sorty of anyway.