It is important to add both a sense of scale and a sense of grandeur to landscape photos.
You add grandeur by using a wide lens and getting close to something (even the ground). That shows the size.
And you add scale by helping the viewer. Adding people is a common technique, as I did in this image of Sedona, AZ, in December last year:
You need to see that image real size to really see it (click through, then select full size). And that brings me to today’s last tip: make it big. Large prints are sooo much better than 4×6 prints.