Sounds more or less like a simple matter of finding the right font/ typeface. Not sure what look you have in mind, but for a nice, pleasant look probably a Gothic type with thin fine lines or a script font would look best. You then only need to overlay it onto your existing smoke using Add or Screen blend mode and take down opacity until it begins to meld with the smoke. A slight blur mikght also help. If you are looking for the opposite and want to cretae the feeling of smoking being bad (which it is of course) use heavy fonts and use darker colors or aggressive blendmodes such as Difference for instance.
For the smoke itself simply create a hollow circle as a custom particle, feather/ blur it slightly, take down the opacity until it is barely visible and use as a custom particle in Particular. Use the Add mode, so when the particles overlap the strings of smoke will begin to manifest themselves. For the motion turn down velocity and work with a negative Gravity and Turbulence.
Mylenium
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