When you enter the Casino Area you are ordered to attack the fighter coming from the left. before you are completely there 2 capital ships arrive, the Star Destroyer and a cruiser, (forgot which one) You hav eto go to the ISD immideatly and try to take it out as fast as possible. You have to make several attack runs for that, so every time you move away from the ISD go into the direction of the casino while taking out fighers. Insave distance of the ISD turn around and make the next attack run.
Remember the Shield Generators on top of the ISD! When you make the attack run, try starting on the front so you have to fly a while over the entire hull of the ISD. If you fly in a straight Line to the Shield generators, the ISD Guns are unable to hit you, if you fly fast(sometimes lowering shields helps) Make blank shots on the shield generator, so no targeting the ISD.
3 torpedos, or 5 missiles will take out 1 Shield generator.