To show how this effect can work in it’s end result I am going to add steam to a coffee photo that I found on Wikimedia commons. If you wish to use this image too you can find it here. Photo by Julius Schorzman.
Create a new document. I choose to create mine at 800×800. This will not be an effect that you will be able to scale up so make sure your original canvas is an appropriate size for the size of the image you want to add the smoke / steam to.
Create a new layer and use the paint bucket to fill this layer with black.
Create another new layer and select the paintbrush and white from the colour picker. You will need to set the paintbrush to various different sizes but keep the hardness to a low level. Start with a mid size brush.
On the new layer, draw wavy lines upwards, using varied brush sizes.
With the wavy lines layer selected in the layers palette, choose Filter > Other Maximum. Keep the radius low.
Repeat step 5 until your lines are quite distorted.
Chose Filter > Distort > Twirl to distort the lines further.
Choose Edit > Transform > Warp
Drag the different points on the transform closer together at the bottom, to give the effect of the smoke rising from a central point.
Change the opacity on the top level to fade the lines into the background.
This layer can then be duplicated and moved around to create the desired effect.
I have used different parts of the layer over the top of the coffee image and added more blur to create the effect I wanted. See the image below for the final result.