Digital Art Effect- How To?

To add to @Mylenium 's great advice, in Photoshop there are always many different roads to the same destination. In this case, there isn't one pat answer, I  mean nobody is going to say "Just go to Filter A and click and you're done."  Open the image you want to work with, and immediately save it under a different filename so as to keep the original untouched. Then duplicate the layer and play with different effects, starting with the ones @Mylenium mentions below.  You'll probably discover new ways to achieve various things as you go along.

You're going to need multiple passes. This is not a single canned effect. You run a Find Edges or stroke a manual selection, then applly some jitter or roughening with a suitable filter (Roughen Edges or one of the painterly filters) then on top run the Craquelure and Fractal Noise filters. It all needs to be tackled in layers and the real trick is to tweak settings and use multiple layer duplicates with blending modes and different opacities and multiple filter instances with different settings. I'm sure there's alsos some old "grunge look" tutorials and similar out there that can help to learn some of the techniques.

Mylenium