Of course what everyone carries will depend on each individual, but this is what I do:
AI computer: Pin retractor secured to front of corset just to the left of the zipper just below the mid-level strap.
Flashlight: I clip the lanyard to a D-ring and tuck the flashlight under the lower shoulder section of the corset (above left breast).
Whistle: Zip-tied to my inflator hose.
Knife: Attached to lower left strap.
Octo: Secured to upper D ring on right side.
Safety Sausage and rattle: Hang together from lowest D ring on right side.
Airhorn attached to inflator hose.
Weights....go in weight pockets.
When we're on our liveaboards (Nekton and Odyssey), they use steel tanks so I need little or no weight, in which case I carry a fold-up snorkel in one of my rear weight pockets. My husband carries the camera since he's the "photographer" in our family.
Hope that helps.