(Note I don't regularly train in KM specifically) Many of the techniques work (wraps, old school punching etc.) However I am kinda "old school" train like you will fight so... first I prefer palm strikes BUT when I do punch I simply make sure
1. proper first structure
2. if striking something hard (say aiming for the TMJ) I make sure I have practiced enough I am hitting with the correct part of the first.
3. I started number 2 slow. first on a speed bag. You can tell a lot about structure and alignment from how the bag reacts. Then worked up to the heavy bag (that helps toughen the fist) then punching the bejeezus out of the thinly padded section of the Mook Jong (wooden dummy, a thinly padded ceiling support in a basement or tree also works well I suppose) I didn't graduate to punching the bejeezus out of an unpadded Mook like some people I train with because a head, as an example, will recoil from a punch, a well secured Mook will not and... yeah not that much of a masochist lol.
but number 2 I mean this. alignment between the wrist and the part of the first striking is important so as to not injure the wrist. When I took Ryushinkan the Sensi taught us to cant the fist slightly down in the direction of the pinky since we would be striking with the top 3 knuckles. In the Arts I now study we use a natural wrist alignment and so aim to strike with the bottom 2-3 knuckles.