I quit long ago, cold turkey. I doubt I was a delight to live with.
You have received great advice from others on how to help your friend.
One of the best things I did, was to avoid trigger locations, mainly places where others would be smoking. Also, I drank a lot of water. I have no idea if it helped, but having a glass in my hand worked for me.
Jennifer
“Live as if you were to die tomorrow. Learn as if you were to live forever.”
-Mahatma Gandhi
"We are what we repeatedly do. Excellence, therefore, is not an act but a habit."
-Aristotle