Which of the following is the first strategy in the management of chronic obstructive lung disease in a smoker?
Smokers with COPD are at high risk for development of lung cancer, which can be identified on a chest CT scan. In advanced COPD, CT scans can help determine the possible  value of surgical therapy.
The two main goals of therapy are to provide symptomatic relief (reduce respiratory symptoms, improve exercise tolerance, improve health status) and reduce future risk (prevent disease progression, prevent and treat exacerbations and reduce mortality). 
Only  three  interventions—smoking  cessation,  oxygen  therapy in  chronically  hypoxemic  patients,  and  lung  volume  reduction surgery  (LVRS)  in  selected  patients  with  emphysema—have  been demonstrated  to  improve  survival  of  patients  with  COPD.  There is  suggestive,  but  not  definitive evidence that the use of  inhaled corticosteroids(ICS) and muscarinic antagonists may reduce the mortality rate.
Smoking Cessation: It has been shown that middle-aged smokers who were able to successfully stop smoking, experienced a significant improvement in the rate of decline in pulmonary function, often returning to annual changes similar to that of non-smoking patients. In addition, smoking cessation improves survival. Thus, all patients with COPD should be strongly urged to quit smoking and educated about the benefits of quitting.
Reference: Harrison’s P R I N C I P L E S   O F I N T E R N A L M E D I C I N E 20th edition page no 1995, 1996
Aminophylline
Anticholinergics
Cessation of smoking
Oral steroids