I have both Lightroom and Photoshop. Is there a tutorial that explains how to make pictures look like paintings? I'm mostly interested about impressionism, but other styles are definitely in my horizon too.
The Palette Knife tool with a fairly large size, medium detail and softness should generate a very impressionist look. You can additionally apply an oil paint filter before or after and it may augment the look. You can find it in the Artistic section in the filter gallery in Photoshop CS6.
Duplicate the layer with the photo, then try different filter effects. In Photoshop CS6 go under Filter > Filter Gallery and try the different effets. Dry Brush and Watercolor are both good ones (dry brush is my favorite). Click on the Brush Strokes tab in the dialog box to try Ink Outlines. That works better with some photos than with others. After you choose an effect or two, you can make that layer semi-transparent for a milder effect. Here's a tutorial on the Dry Brush effect: http://www.youtube.com/watch?v=iD7dNJUIpnM