While playing around with my tabletop photography one day, I decided I would try out one of the several tutorials that you can find online for making smoke. First I needed an image to try it on, so I grabbed a kneaded eraser and jammed the spoon part into it so the handle would stand free of the sides of the cup. I wanted a photograph of STRONG coffee, so strong that a spoon would stand up in it. Then I set the cup on my black velvet -covered tabletop and filled it with coffee (the cup, not the tabletop). I had viewed a few videos that I found by searching for smoke tutorials and decided to use one I found on YouTube posted by Iceflow Studios. It involved creating a shape with the pen tool and applying a number of filters to the shape, then using the cloud filter and working with the blending options. There is probably an easier way of doing this, but I liked the result better than others I tried and liked the no-nonsense video it was based upon. This shows the progression of the technique.
And here is the video by Iceflow Studios: