Try it with a group, or with a police, but stay away from nuns. To stay alive, you gotta smash them buildings. Try smashing them from the top. To surgically remove each floor, try kicking it. To reach a closer building, try the back smash.
Jump kicks are awesome for helicopters, but useless for building attacks.
Finally, keep an eye out for foods and what not during your destruction. In short, down and jump will not only shake out humans for you to eat, but also collapses the top floor. Quick and painless. To ride on tanks and super hover craft thingys, press down while jumping on top of it. When travelling, always keep your stuff together.