Chum the area a bit and put out a selection of baits. A big salmon/mullet head and a live bait (big mullet, big yakkas, tailor) under a balloon. Preferably give the livie a little tiny wound so theres a small scent of blood in the water coming from it. In the Harbour, head up into middle harbour. Anchor in places where theres deep water (10m+) and good current flow. These are the sorts of places where sharks are likely to be actively feeding. Its worth having an unweighted bait too. This will woft around in the current until something has a crack at it! For the Hawkesbury, i find them almost anywhere. If you burley hard then you should have a little bit of luck! I have to agree with the previous comment though, the sharks will be harder to get through the cooler months. If i were you i'd hold off until september at least.
Cheers, Tom