To destroy the enemy you must first dehumanize him - this makes it easier to convince your citizens of the nobility and morality of your task = - Qaddafi, Saddam and Chavez all got the same billing - they are irrational , unpredictable and violent - men who visit upon their peoples depraved acts - we are good and they are evil.
The second thing you must do is grind away slowly at his resources and capabilities - ensure that he poses no threat - chief among these is to remove any air superiority, he might have . Resolution 688 gave us that in Iraq in 1991 - ostensibly to protect the Kurds the real objective was to destroy Iraq's capability and ensure air superiority for the invasion to come.
The third thing you must do is find an ally on the ground - war lords will do, ISIL will work in a pinch - all you need is to reduce your enemy's capabilities.
The fourth thing you must do is find a pretext for invasion - a chemical attack will do- false flag if you must.
voila- war