Well as they; say you can't make omelet whitout making masses of enemies.
Of course, always:
I can't plan how answer question in test night before it
I can't know how you enemy will respond my attack, if I don't know your enemy
I can't say person to be my enemy, if I don't know him
There is always knowledge and presentiment, and those can be used, but there is also luck that can't be controlled. So, plan how to use knowledge and presentiment, and conform to the luck(also contain error analyses). When its time to act, don't hesitate(It's easy to say).
and about destroying enemy:
I haven't have enemy that is worth of my time, but if I have change, I can waste few minutes to make my point clear. But if I have good reason to destroy someone, I will do it.