Personally, I think the "key" to people being successful when they move from smoking to vaping comes down primarily to getting the right juice. You have to like the taste, and you have to have the right nic level. If your juice is a flavor you like with the nic level you need, you're almost all the way home. I'm a big fan of variable voltage devices (even the low end ones like the ego twists and vision spinners and such), but the juice is the key, IMO.
I was a 3 PPD smoker before I started vaping, and it took me several months to get off the cigs. One of the best pieces of advice I was given early on was "It's OK to smoke. Vape when you want, smoke when you want, and if you want to quit, it will happen. Smoking a cig isn't a failure. Don't count the ones you smoke - count the ones you *don't* smoke."
I started vaping at 24mg nicotine. It didn't take long before I was down to only a few cigs a day, almost all of which came right after meals, but I couldn't get rid of those last few. For several months, I was still smoking right after I'd eat, and no amount of vaping would help.
Then I bought some 30mg nic juice. The day I got that, I stopped smoking, and it was easy. I didn't even use the 30mg most of the time. Since 24 was working as my "all day", I just used the 30mg juice after meals or when I'd feel particularly stressed, and the 24 the rest of the time.
After six months or so of no cigs, I started to cut down on the nicotine a little at a time, and now I vape with no nic.
So if you're having issues with those last few cigs, I'd suggest trying some juice with a higher nic level. It worked for me.
And if you never, ever, get rid of those last few cigs, that's OK. Really, it is. Just by getting rid of *most* of your cigs, you've made a huge step forward. But I do know a few people who vape a lot, and smoke a few cigs a day. They are still far better off than they used to be. And who knows - maybe one day they'll quit smoking for good.