are you looking to just suspend your model or are you looking to hang your model by the neck?

If you are just suspending the model you should use suspention cuffs. It will not cut off the blood flow. If you are going to hang your model by the neck extreem care is needed and it should be for the shortest time for the shot. Care should be taken that she does not swing or sway or have any kind of shock to the hanging. Also I would adive not having a model over a 100 pounds.

I would advise to use a whaist belt to take the load off her neck. It could be hiden under clothing or photoshopped away in post producktion.

Be very carefull