This tutorial will show create a really simple smoke effect.
Step 1 :
Open up the image you wish to apply smoke to, i will be using this image of a v6 CLIO.
Step 2 :
Create a new layer call it SMOKE.
Step 3 :
go to FILTER > RENDER > CLOUDS
Step 4 :
Go to the styles menu on the layer pallet. Select blending options.
Step 5:
The section we are going to be working with is the BLEND IF section.
I have cropped round this. While holding down the alt key, drag the small triangle.
You should see that it has split. continue dragging it all the way over to the left.
Step 6:
You image should look like this now, You can use the eraser tool to remove unwanted smoke. I'm going to make it so the smoke is coming from the font tyers.
on the layer pallet. Select blending options. 
