Most of Go Rin No Sho uses hard to understand words and juxtapositions. Without a background in certain military fields or basic human history, you will have a hard time to comprehending what is being communicated here. Even with such a background, you may still fail to comprehend due to some flaw in your perspective. For example, the OODA cycle invented by USAF Colonel John Boyd has proved that if you can get inside the enemy’s decision making process (his OODA cycle) you can get a jump on him. In combat, this is a decisive advantage that allows you to annihilate the enemy, even if he should have superior numbers or resources at his command. Now, with that idea in your mind, read the section of Go Rin No Sho above here again. Perhaps you will see a connection with your more perfect perspective: more than you had seen before.
As applied to Target Focus Training, the three precepts listed here becomes very simple when applied to practical examples. Ken No Sen is when some guy starts bothering you in a bar and while you two are facing off each other trying to intimidate each other, you pull out a gun and blow his brains away unto the bar top. That is Ken No Sen: to attack first and with overwhelming might while the other guy is still getting ready. It would also apply to a First Strike attack with nuclear missiles.
Tai No Sen would be a woman who pretends to be cowed and frightened, and when the attacker lets down his guard, the woman attacks with decisive strikes (decisive in that the target dies).
Tai Tai No Sen would apply to a knife wielding assailant who tries to cut you, and instead of blocking his strike or backing away out of his range, you close the gap and interrupt his attack with a strike towards the throat or body. The knife is only dangerous at the tip, while your body and arms are dangerous at any range where you can touch another with it. Tai No Shen would also be seen in Bruce Lee’s “Intercepting Fist” concept where instead of passively waiting and blocking the opponent’s strike, you attack him as he is attacking you, but you connect first, thus stopping his attack.