You want to know the best way to not get COPD? Don't smoke. Don't start, and if you smoke now please stop. That's it. That second hand smoke stuff doesn't help either.
I may seem a little cheeky on this one but it's so simple. You are 12 times more likely to get COPD or another lung disease if you smoke than non-smokers. Sure there is second hand smoke (which also means don't smoke yourself - you are cuasing COPD in others which may include loved ones), and chemicals like air pollution, fumes, and even dust. But really - just don't smoke.
Here is the biggest problem with COPD:
Damage to the lungs caused by COPD cannot be repaired. If the disease is found early, though, it might be possible to slow it down.
That's right - unlike other health issues, most of which - including heart disease and cancer - can be addressed in some manner and even cured and reversed. But not COPD, so - yeah you guessed it - don't smoke.
In summary - DON'T SMOKE. For your health AND others'.