How to Transform Dull, Lifeless RAW Files Into A Stunning Natural-Looking Landscape Using Photoshop?

Photoshop can only do so much. It is better to get a great image straight from the camera, rather than trying to wrangle a poor image into shape.

That said, not all shooting situations make for great photographs. You might need to try things like exposure bracketing (which Photoshop can stack into an HDR image), long exposure (best with a tripod, wide angle lens, and possibly a neutral density filter), or a circular polarizer filter to improve the shot.

If you're stuck with the raws you have, see what can be done in Camera Raw. You can do quite a bit with just the Basic and Tone Curve controls, and the lens corrections can be very helpful if your lenses aren't top notch.

Beyond that, you simply have to find what you don't like, and do the best you can with what tools you're given. If you aren't sure where to begin, perhaps you need to look at the galleries of others, picking out what makes their images memorable, so you can expand your own 'vocabulary'.