On this video tutorial (part of a longer series), Aaron Nace from Phlearn demonstrates how to dramatically improve landscape shots in Camera RAW.
This video starts (around 1:00) in Camera RAW with a rather washed out image of dunes. The whole idea of this video is to show you how you can very easily target different areas of the image with an adjustment brush and change them to reflect the way you want them to look.
You can start by choosing to mark the mask – it helps you to see exactly what you mask and what you do not. The whole idea of the adjustment brush is the fact that you can locally “play” with all the settings that you normally apply to the entire image. You can also do this in Photoshop itself but we tend to find that doing this in Camera RAW is simpler and faster.
Nace applies a specific adjustment for the dunes (making them darker) and than moving on to fix the skies using a new adjustment layer (you can choose a specific adjustment layer with the mouse by choosing the right one when the overlay box is marked).
This is a pretty straightforward tutorial but it is helpful. Nace published several other related videos including a longer one dealing with adding color to your landscape photos in Photoshop itself.