Before the mission starts get the cops after you. Then, destroy any you see! The Chaos Bar will go up a lot faster if you actually do what Mitch said. Grab an Angel, and then destroy things! You will need a powerful weapon like an MP5.
Another very useful method to complete this mission is to put on the Cop uniform by going to the police station in Washington and heading into the locker room (the mission "Cop Land", which is part of the Vercetti Estate missions must be completed). Grab a helicopter from the Vercetti Estate's roof and fly over to Fort Baxter. Because you have the Cop uniform on, the soldiers there won't shoot at you. In one of the towers will be an M60 machine gun. Pick it up, save the game and head back and pick up another. Then start the mission. First, get a 3-star wanted level by using any weapon aside from the M60. Once the Police Maverick comes onto the scene, put every single bullet you have for the M60 into it, until the helicopter blows up (even when it begins to fall from the sky, continue to shoot it). This will more than likely earn enough points to finish the mission, but if not, simply destroy a few more police cars or kill an officer or two to fill the bar.
The safest and fastest method to accomplish this mission is by using a motorcycle Anjel firing several cars and destroying them. The chaos meter will skyrocket, and it is not necessary to kill civilians and police officers. It is recommended explode parking cars which is near where the mission begins, it is an isolated place and not bring police attention.