You can easily create smoke and particulate effects in post, but doing them well is another matter.  Sometimes you just can't beat good old practical effects.  Here's my most recent invention:

Miniature smoke generator

You'll need:

- dry ice

- hot water

- protective gloves

- stainless steel popsicle molds

- ring clamp/plasticine/something to hold the molds

- silent handheld fan (optional)

Place the mouth of your stainless steel popsicle mold(s) where you want to the smoke to emerge.  Once the mold is secure, fill the mold almost to the brim with hot water.  When ready, drop a few pieces of dry ice into the mold.  There's a chance a single mold won't emit enough smoke, so think about using entire ice cube trays instead.

The smoke from dry ice tends to sink toward the ground, so you might want a fan to blow the smoke into a specific direction.  That's where the handheld fan comes in.  If there's enough space, you can attach the handheld fan to the molds using tape or a rubber band.  Some handheld fans can be noisy, so try to pick up a noiseless one unless you're willing to pay for ADR sessions.

Now you're set to fill your scene with some character.  Have fun, and make sure not to handle dry ice without protection—it can burn you in a split second.