Summarize:

Either right-click on the background layer, then choose Duplicate Layer from the menu, or drag the background layer to the New Layer icon and Photoshop will create a duplicate layer automatically. This may make the image too dark, but it is only an intermediate step. Once the blend mode has been set, select Control-I (Command-I) to invert the image, or choose Adjustments from the Image menu, then select Invert. From the Filters menu, select Other... > High Pass... Make sure the Preview checkbox is enabled, then adjust the Radius slider to taste. Notice your image will change, with a nice, soft effect. The radius really depends on the resolution of your image. If it's very high resolution, you will use a larger radius than if it's a low-resolution image. Let your taste be your guide. While we're using it with a landscape, this effect is also very nice with portraits. With the Background copy layer selected, click on the Levels icon in the Adjustments window. Clicking the Auto button will automatically balance the levels between the brightest part of the image, and the darkest. You can use the sliders to fine-tune your image, or use one of the custom presets at the top of the Properties window. Click back to the Adjustments tab, and click the Curves icon (to the right, next to the Levels icon). This will let you fine-tune the contrast of the image. Click about 1/4 of the way up the line and pull it down just a little bit. Click again about 3/4 of the way up the line and pull up just a little. This should form a kind of "S" shape, and your image should be much more dramatic. This will prevent the contrast from affecting the color information of the image. From the Layers window menu, select Merge Visible, or press Control-Alt-Shift-E (Shift-Option-Command-E on a Mac) to create a new layer that merges all the information into one layer. The Doge and Burn tools are ideal for bringing out highlights and shadows in an image. At the top of the Photoshop window, set the controls as follows: for the Dodge tool, set the Exposure to 5%, and the Range to Highlights. Set your brush to a fairly small size (depending on the resolution of your image), and use the Dodge tool to boost the highlights. It's great for bring out details in an image, without over-brightening things The Burn tool will darken things, and is well-used on shadows to give images greater depth. On top is the before image, followed by the edited version.
Duplicate the background layer. Set the Blending mode to Soft Light. Use the High Pass filter. Create a Levels adjustment layer. Create a Curves adjustment layer. Change the Curves adjustment layer's blending mode to Luminosity. Merge Layers. Select the Dodge tool (O). Compare the images.