You can organize your body points act-by-act:
- Body 1: Act I (Iago plays the race card against Brabantio and the Duke)
- Body 2: Act II (Iago plays the reputation card against Cassio)
- Body 3: Acts III-IV (Iago plays the jealousy, misogyny cards against Othello and Desdemona)
You can apply "The Sixteen Villain Archetypes" to Iago, using quotes from the play as support.
Here's three of the major villain archetypes that apply to Iago:
I. The Devil
the charming fiend, he gives people what he thinks they deserve. Charisma allows him to lure his victims to their own destruction. His ability to discover the moral weaknesses in others serves him well. Close your ears to his cajolery – he’ll tempt you to disaster.
II. The Traitor
the double agent, he betrays those who trust him most. No one suspects the evil that lurks in his heart. Despite supportive smiles and sympathetic ears, he plots the destruction of his friends. Never turn your back on him -- he means you harm.
III. The Schemer
the lethal plotter, she devises the ruin of others. Like a cat with a mouse, she plays with lives. Elaborate plans, intricate schemes; nothing pleases her more than to trap the unwary. Watch out for her complex designs – she means you no good.
In short, he's a traitor and backstabber to Othello, Emilia, and Cassio. He's an Schemer / Evil Genius who cannot stop waging war, even after the war with the Turks is over. He's so evil that he who wants to destroy everyone, including himself. Ironically, at the end, he survives as a mute.