I love to shoot landscapes - I'm fortunate in that I currently live in a very scenic Australian State where landscape photography is a must.
At times, it's difficult to convey a sense of scale with an image - I know the depth and breadth and height because I can see it with my eyes, but I can't necessarily convey that to someone who is viewing my photo.
One technique to give your images a sense of scale is to bring people into them, because people give us a familiar point of reference - we know the approximate size of a human being therefore it completes the picture and gives a sense of the true proportions of a landscape.
This also works for indoor and outdoor architecture. Notice the difference between these images and how easy it is to grasp the scale and size of what we're looking at when humans are in the photo.
If you browse through the images below, you will notice that we get a much clearer understanding of the size of the largest elements in each when we can see people.
So next time you pack up your camera for some landscapes or architectural shots, makes sure you snap a few images with one or more people in it - they will add just that little bit more to the story you wish to tell with your photos.