Most Helpful Girl
I think quitting cold turkey is more effective. They need to do a complete overhaul of their habits. Constantly having a stick in their mouth and nicotine in their lungs does not help them get over cigarettes. It can take months for new habits to form or old habits to die. They will probably go back to regular cigarettes in a heartbeat because they never had a chance to lose these habits, and e-cigs don't "feel the same".1
Most Helpful Guy
E-cigarretes, at least is a healthier choice, and part of the addiction
is indeed to have something in their mouth.. is why certain gum works as well.
There's some book that's said to have made
a huge number of people quit smoking, unfortunately
I cannot currently recall the name, but perhaps you can
find it through a bit of searching.
Another method I've used myself, was that whenever a friend was
lighting a cigarrete, I'd throw away a coin (money).
It plays with their feelings and it actually made
two of my friends quit after a little while.
It's not a 100% certainty, though. ^.~0