family member wants very much to stop smoking, but doesn't know how to do it.
The first thing to do is let this person know how important it is to you that they try to quit. Do your best not to nag or bring it up in a way that will make him or her totally close the discussion. Instead, you may want to say something like: "I love you. I want you to live a long and healthy life." Explain how their smoking makes you feel -- both mentally and physically -- and try to be gentle, honest, and loving.
If someone isn't ready to quit just yet, you might make a request about where and when this person smokes. For instance, you can make a rule that he or she never lights up when you're around, or declare some rooms "off-limits." These new limits might make it easier for someone to quit in the near future.