I learned a great trick from a cop about intercostal breathing.
One of my country singers was a policewoman, and one day she showed up for her lesson on her way to work. She was in full uniform—boots, gun, hat, handcuffs, and bulletproof vest. She started to take the gun belt off, but I stopped her. I thought it could have an interesting effect on her singing. Seeing the outfit as a costume, I wondered if it might make her feel more powerful or perhaps more aware of the energy under the gun belt encircling her abdomen.
But the thing that improved her singing most was the bulletproof vest. It helped me explain intercostal breathing, which involves expanding the rib cage on all sides, and opening the lower floating ribs to hold a reserve of air while breathing. When the singing policewoman expanded her rib cage, pushing it steadily against the sturdy bulletproof vest on all sides, she could really feel what I was talking about. And her voice became richer, fuller, deeper, and lovelier. (Of course it’s a true story! How could I possibly make this up?)
So go to a thrift store, get a snug-fitting suit vest, and wear it while singing. Feel your rib cage expand against it on all sides as you inhale. Then hold your rib cage with a steady pressure against the vest while you breathe beneath it with your diaphragm.