The first thng you have to do .. is STOP WORRYING. A COPD diagnosis is NOT a death sentence. It's a slow progressive condition that can be 'managed' very well if you do all the right things.
You've already stopped smoking and that's great. Next, you have to exercise .. and exercise and exercise. Walking at a nice brisk pace is the best, I think, but any regular aerobic exercise will improve your lung function massively.
Take your meds, religiously .. if one doesn't agree with you, tell your doctor who will prescribe another. If you get breathless a 'puffer' should help, but not everyone needs one. There are some interesting new findings on the benefits of taking Vitamin D3 (It has to be '3' apparently) if you have COPD .. I started taking it about 9 months ago, and it helped me a lot. But everyone's different so speak to your doctor first.
Look after yourself. Eat good food, and get plenty of sleep .. don't lay awake worrying. Just DON'T.
Have your flu jab. DON'T FORGET. And during flu season .. and just generally during cold weather when colds and flu are more prevalent .. try and avoid crowds, and people who you know have colds or bronchitis. I know it can be difficult when you have to work and mix with people .. but do your best, and try and wash your hands as often as you can during the day.
At the first sign of a cold (which may spread to the chest and affect your lungs) I always use something called 'First Defence' .. a nasal spray which blasts the cold virus before it gets in the system. It may work, or it may not .. but I haven't had a so much as a sniffle in 5 years.
Keep checking this site.. it is the BEST source of info on the condition .. because it's peopled by those who have it and who know what you're going through. I don't think I'd have got through the first couple of years of my diagnosis (I was absolutely certain I was going to die!) if it weren't for this site.
I'm sure others here will have their own tips and contributions to offer, but I'll leave you with something my consultant said to me once: 'If you look after yourself, take your meds .. eat well and exercise often, there's a every chance you'll live a long and happy life. And yes, you might die WITH COPD .. but you won't die OF it'.
Good luck Marcus.