This is a very good tip for low viz from Foxfish.
You choose a promising spot, lay down on the bottom and look up to the surface brightened by the sky above, so that a counterlight effect will help you recognize the dark shape of fishes passing in between.
Otherwise, stay hidden and "call" the fish, making little noises and/or vibration: not too loud not to scare them away, not too quiet so to capture their attention and drive them towards you for curiosity.
But the subsequent question is: what is a promising spot? where to go?
In facts you must know where there's more probability that some fish will be passing by. And this is THE question about spearfishing.
More specifically related to very, very, very low viz.
In low viz the fish as well need some familiar point of reference, and they tend to move along a pattern given by recognizable things or objects: they will be likely to pass by rocks bigger than the average, kelp bushes, pieces of pipeline, boat docks, wrecks or any sort of familiar submerged structure.
These are the best places to perform the counterlight hunting suggested by Foxfish.
But this does not say it all, of course.
Also remember current and tide. Fish are always in search of food.
Predator fish like bass tend to hunt against the current, to intercept the stream that brings food onto them. If you perform aspetto with the current from your back, that will normally help.
From what I have experienced, a fish must always have a good reason to choose a place to stay or to go to instead of another: that's related to period of the year, food chain events, weather/current events, reproduction events, type of bottom chosen by each species as a favourite habitat, and also the perception of "safety", and the prediction of food availability, that a fish may have in a place or another.
Just ask yourself some questions:
First. Where would you go if you where a fish?
Second. Is there any species which is spawning, making eggs or breeding newborns in this period of the year? What's the depth and type of bottom chosen by that species for reproduction? That's where you have to go! It's a bit unfair and slightly cruel to shoot a fish in love or breeding (provided it's not illegal: don't do anything illegal, never!), but many other antagonist species will go there looking for eggs and newborn to eat: reproduction of "enemy" species stirs up the food chain as well as current, weather and tide.
Long post! Hope it's not too boring (it was intended for newbies)