What is the most interesting, the land or the sky? Whichever is the most interesting should be emphasized. If it is the land place the horizon on the top third or higher. If the sky is more interesting place the horizon on the bottom third or lower. Let's discuss this image:

While the sky is busy lighting up and you know where the action is going to be start looking for something of interest to place in the foreground. I went with this green bush. I broke the rule by placing it in the center (horizontally).  Now how do we emphasize the sky to maximize its impact?

• Shoot from a low angle. I am shooting at knee height here. You want to be shooting up to include lots of sky.

• Leave space between the top of your foreground object (if possible) and the background objects or the sky. If I had gone much lower the green bush would have not been separated from the mountains in the back. Without that separation you loose depth.

• Go wide to create a big sky and to shoot almost above you.

• Get really close to your foreground object to make it seem larger.

I regularly see people shooting at eye level. Try lowering your angle, especially if you want to feature the sky. Think skyscape, not landscape. Go where the color is. Go where the most interest is. Angle that camera upward with a really wide lens and you can get some really nice images.