In the case of the photo shown above, I worked with layers and several filters, adjusting opacity to achieve an effect I liked. The image was originally in portrait mode with clear sky above the clouds (see below). I cropped that to make the image landscape and have the clouds dominate the sky. I added significant noise, some Gaussian blur, torn edges, and ink outlines via Photoshop’s filters and then made level adjustments for brightness and darkness.
There are also various plug-ins on the market, and I have found that there is no real substitute for experimentation and seeing what the filters do at their extremes. Ultimately, you find an effect that pleases you, regardless of whether it looks more like an etching or a lithograph or something else.
What do you think?