Your going to need the default cube(emitter),a sphere mesh(smoke),and the particle system(for animation). Select cube and add a particle system to it by pressing '+' symbol in the panel. Give it the name Toon smoke fx.
Now pressing the play animation or ALT A, you'll see the particles in motion.
What you want now is to have control of particle direction.
Go down to the Velocity part of the panel and adjust Emitter Object.
My setting are
But adjust however you want it.
Once you have your direction under control, Go to the render section of the panel Uncheck Emitter(So it doesn't show up in your finals), change Halo to Object,and add the Sphere in Dupli Object.
I named my Sphere_smoke object.
Should have something like this in the 3d viewport.
Add a material.
I'm now going to add a shadeless white material for simplicity to the Sphere object, so Freestyle lines can pop out when rendered.
Now for some Freestyle fun:)
Turn on Freestyle by going to the Render panel.
Down in Post Processing and checking the Freestyle box.
Freestyle section will open up in the render panel. You can use one of many cool preset style modules but you have to be in Python scripting in Control Mode section.
But for this we'll just use Parameter Editor mode for user friendliness. Hit the '+' symbol to add a custom style. My settings.
Not to far down from this you can find Freestyle:Line Style
I added a Calligraphy modifier because I love that thick brushy look it produces.
My settings below.
Now hit F12 and you should get something looking a lot like this.
Here is a low res animation.
This effect comes in handy for rockets,car tires,old steam punk trains etc...etc...
You can really push the NPR look for this a lot further with materials,modifier stack and textures.
It''s only the beginning.