What kind of breathing exercises would you recommend for someone with copd?

Pulmonary rehab. If it is available many communities offer a program called pulmonary rehab. This is a graded exercise program suprevised by trained respiratory and physical therapists and in some cases physicians. COPD patients are also educated in specific breathing techniques and about their disease in general. It seems patients who go through the program do overall better.
Deep slow breaths. Deep slow controlled breathing will help the healthy parts of your lungs operate more efficiently, making up in part for the lung tissue damaged by COPD.
Pulmonary rehab... Patients with COPD can be taught breathing exercises as well as exercise under medical supervision in pulmonary rehab. Your doctor can recommend a pulmonary rehab program for you. This program is often very helpful.