If I am carrying my messenger bag, they go in the hard case in the bag.
If no bag, but hoodie, jacket or shirt with pocket, they go in a pocket.
If no bag, hoodie, jacket or shirt with pocket, I carry them in my hand, unless I need my hands, in which case they hang from t-shirt collar, front or back, whichever is more secure or comfortable as circumstances dictate.
Some things I have seen people do that I do not do:
Worn "backwards"; earpieces over ears, but lenses on back of head.
Worn under chin; earpieces on temples, lenses pointing down.
I hate the way these styles look.
No hanging from mini-bungee cords either.
Also don't wear them on top of my head; I just don't like it.