As a smoker who worked for a boss who clearly hired me with the announcement that he hated the smell of ashtray...
Washing your hands after every cig, listerine strips... that will do it.
I worked at a different place after that and got in the habit of it. MOst people there didn’t even know I smoked! The hands are the foulest smelling part of a smoker.
My dad smoked three packs of Chesterfields a day.(none of those sissy filtered cigarettes for my dad.)
He had permanent nicotine stains on his fingers.
There were even stains on the arm of his favorite chair.