Go into them without an clear end in mind.
Go into them with agendas that try to put lipstick on the pig that is war.
Go into them with "we always done it this way" mindset.
Go into them without learning from the lessons of history.*
It is said that if you know your enemies and know yourself, you will not be imperiled in a hundred battles; if you do not know your enemies but do know yourself, you will win one and lose one; if you do not know your enemies nor yourself, you will be imperiled in every single battle.
There is no instance of a nation benefiting from prolonged warfare.
If fighting is sure to result in victory, then you must fight, even though the ruler forbid it; if fighting will not result in victory, then you must not fight even at the ruler's bidding.If you can't clearly define "victory" then why the hell are you fighting?
First, the read CDR Salamander: Shaping the Blame in Afghanistan
Then, the listen:
Listen to "Episode 519: Going Sideways in Afghanistan & Iraq, with Daniel P. Bolger" on Spreaker.
*Sun Tzu has a lot to say that makes sense. Americans tend to read these quotes but often lack the patience to follow the advice.