Maybe this final image looks grimly and gloomy, but if you are in the mood for quick and simple Photoshop tips and tricks, this is a tutorial for you. I just wanted to add yet another tip: if your clouds (from Filter > Render > Clouds) don’t look misty enough just apply Filter > Blur > Gaussian Blur to soften them a little bit.
Check it out!
You can find it here:
Realistic Mist Tutorial