How can I improve my landscape photos

I never been happy with my landscape photos. They always look over or under processed or just shot incorrectly. I am looking for suggestions on how to minimize my shooting errors and what I should try in Lightroom.   I took some photos in mid morning of a water fall and canyons. Sun created bright areas and also strong shade. I tried a number of settings wide open down to about f11.  I tried over exposing and also under. I tried making corrections in Lightroom and the attached photos are about the best I can get. I shoot in raw, set the camera to aperture, auto ISO, Auto WB and matrix metering. What should I have done to overcome the sun/shadow issue or is there something I could have done to take advantage of it?