Basically any exerciss wherein you really get yourself USED TO breathing through your diaphragm will help.

I offer a few that I hope will help:

Lie on the floor. Bend your knees and keep your feet planted firmly, spreading your legs slightly. Press your lower back into the floor; as you do so you find you have to contract your abdominal muscles. Do this repeatedly, contracting the abs muscles and holding your lower back muscles against the floor for five second; then release for five seconds.

Once you get THAT down, practice breathing in and out with your mouth open (form some sort of vowel sound with your lips, like "ooh") and using your diaphragm as you do so. Start with five seconds breathing in, hold for five, exhale for five, then gradualy extend the count to ten seconds.

Next step: add vocalization. Breathe in on a count of five, then sing the "ooh" sound for as long as you can, (feel your diaphragm muscles working), but instead of gulping in air as soon as you run out of breath, see if you can pause and hold slightly before slowly breathing in again; this will help you develop better breath control, which is not just about singing/exhaling, but taking IN breath effectively as well.

Lying on the floor allows you to feel the diaphragm muscles work naturally. You can practice this breathing exercise standing up, too, but place your hands on your abdominal area and lower back to feel what those muscles are doing when it seems to be "working." Continue to check this; you want to train your body to be able to repeat this technique without having to think too consciously about it.

Also, a few minutes of slow breathing (inhale for ten seconds, hold for ten, exhale for ten) as part of your usual pre-performance warm-ups should help immensely.

I hope this was helpful.

Peg

who learned how to breathe, more or less, in voice class in high school but had to relearn it all when she started singing traditional music...