This is usually what I do:
Get an i/LAAT (or whatever it is) gunship and pack it full. Head round to the Techno Union Ships, and blast them as much as you can. By the time they almost explode, the AT-TEs will be heading past the spire. Use them to spawn Jet Troopers to the west, and infiltrate the Spire hangar. Blast the droids in the war room and capture the spire. Hold onto it as much as possible, as the Seperatists are now suffering a Reinforcement Drain. The bulk of your forces should now be defending the Assembly Area, and the Derelict, as if they're taken/destroyed, you'll end up having your gunships gone, or most of your units bombarded as they try to retake the Derelict. For that, I usually mine the derelict passes. When the Seperatists are almost finished, bring a force to the East and West Bunkers and capture them to end the battle.
Hope this helps.