A rule of thumb is to look for major points, crevasses and pinnacles/bommies that are exposed to some kind of water movement ie current, waves, surge etc. Fish may be patrolling these areas or holding in back eddies. Work the whole area in general but approach with caution and concentrate on the leading edge where this water movement is hitting.
As Travis mentioned, working bait schools are also likely to hold fish. In the places I fish, such occurance usually holds school sized/rat GTs but this may not be the case in other locations or special conditions.