There's been a lot of discussion lately (nothing new it's been around for 1,000's of years, just more if it) regarding breathing patterns. In particular, the importance of diaphragmatic breathing and its role in postural function by means of improving the "inner unit" activity.
The idea is to work specifically on diaphragmatic breathing by way of focusing on the intake of air and the expansion of the entire abdominal region (anterior/posterior/lateral). Patrick Ward and Carson Boddicker have been going into great detail the specific mechanics of this form of breathing. I suggest checking out their blogs if interested in more detail, they both have great information.
Here's a blog post I had from a couple years ago regarding breathing:
Breathing and the Spine
To add to some of the concepts, my thinking is that focusing directly on breathing might not be the best route to take when trying to improve a breathing pattern dysfunction. The reason being, is that breathing is an autonomic process and in the history of human kind is not really "natural" as something to have to worry about. Of course we are in a day and age where everything is a little 'screwed', but I think it's might be more effective to work with the sensorimotor system with which we have greater voluntary control over. Obviously we have, or we can develop great control, of firing specific muscles or muscle groups, and in the case of an altered breathing pattern we tend to use an 'upper-chest' technique, utilizing the muscles of the chest, shoulders and upper back. I have found it to be fairly successful in working on just relaxation of those muscles. If these 'upper-chest' breathing muscles are neurologically quiet, then what other option do we have than to resort to diaphragmatic breathing? ... plus the skill of muscle relaxation will go a long ways in improving motor control and potentially skill; not to mention the potential effects of reduced anxiety, etc... If one can truly relax, breathing usually falls into a normal, healthy rhythm; brain waves, heart beat, all of physiology falls into a more coherent state.
So much goes into muscle activation these days, but so many coaches miss the point that it is equally important to have the skill to relax muscles. But to take this even further... what's the root cause of excessive muscle tension and abnormal breathing patterns? What's the cause of the anxiety that causes the excessive muscle tension and abnormal breathing patterns? What's being done about those causes? The key is to keep asking questions? All those things need to be considered and dealt with. Dealing on one end, just the mechanical, may or may not, stop the leak while it is still "pouring rain outside"... and even then it's still just one small piece of a puzzle (cliche... I know), not the magic bullet. ... AND it's just another symptom, but I digress.
Some specific techniques:
Progressive muscle relaxation
... or a classic, "Relax and Win" by Lloyd 'Bud' Winter, if you can find a copy... (or for a great overview of Bud Winter and "Speed City" email Carl Valle (elitetrack.com) about his the mediacast he recently put together)
.... or any Relaxation Technique... which could just lead back into working specifically on breathing... so then, I guess, just find what works best for you or each individual. Have options and keep asking questions.