Play it loose.

Hit 10 enemies with your melee attack. (campaign only)

Kill an enemy by tagging him with a sticky grenade. (campaign only)

Engineer an exit strategy.

Kill an enemy just as they are throwing a grenade. (campaign only)

Recover one Intel Item.

Use your wingsuit to reach the Southern island.

Kill Vaas.

Complete a WANTED Dead quest.

Rescue Keith from Buck.

Activate 9 radio towers.

Rescue Oliver from the pirates.