Stop smoking before surgery

Studies have shown conclusively that patients who stop smoking before surgery have fewer complications and heal faster than those who continue to smoke.
Smoking and wound healing
2012 systematic review concludes smoking delays healing in surgical patients

The objective of a large 2012 systematic review was to clarify how smoking and nicotine affects wound healing processes and to establish if smoking cessation and nicotine replacement therapy reverse the mechanisms involved. In total, 177 articles were included. The author concludes that smoking has a prolonged effect on inflammatory and reparative cell functions leading to delayed healing and complications. Smoking cessation restores the tissue microenvironment rapidly and the inflammatory cellular functions within four weeks. 

Sorensen LT.  Wound healing and infection in surgery.  The pathophysiological impact of smoking, smoking cessation and nicotine replacement therapy.  Annals of Surgery 2012;  255: 1069-1079.