Send Han straight ahead, aiming for the small asteroid next to the TIE Fighter and pushing the large asteroid for some extra points. Shoot Tarkin during flighr. Send Leia to pop both pigs on the northwestern planet, and use her tractor beam to try to pop as many remaining pigs as possible. If necessary, use Han to snipe any remaining pigs and to push the large asteroid to its doom.
See Video Walkthrough.